Sandy Beaches

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					    Beaches
Sandy
   And
  Mollusks

      #7
 Packet

  Marrne
Biology[Jnit
                                                                                  Name:
                                               Packet #7 Revicw Qgestions

  l.    Dcscribc how abcach is forncdby     wavcs.

  2.    Explain wtry a beach is never the samc the next day.

  3.    Describe what a sand crab is and where it is located.

  4.    Color the following animals of the sandy beach and explain why they live in the specific area they live
            &     Ghost crab
            b. Sand crab
            c. Bean clam

 5.     What are the soft bottoms of the continental shelf made of and how does it occur?

 6.     Explain where epifauna and infauna live.

 7.     How do worms eat in the soft bottom areas?

 8.     Color the following animals of the soft bottom and explain how they are adapted to the area
            a. Pacific sand dollar
            b. Moon snail
            c. Angel shark
            d. Pismo clam

 9.     What causesthe diversity in mollusk structure and shape?

 10. What is the function of the following parts of the bivalve?
        a. Siphons
                     i. Incurrent
                    ii. excurrent
        b. Foot
        c. Shell
        d. Mantle

 I l.   Describehow the followine bivalveseat?
           a. Cockle
           b. Mussel
           c. Scallop
           d. Soft-shellclam

12. Color the following partsof bivalves
        a. Incurrent siphon
        b. Excurrent siohon
        c. Foot
        d. Shell
        e. Mantle

13. Cive severalcharacteristicsof gastropods.

14. Color the following structuresand give the functions of the following parts
        a. Operculum
        b. Foot
        c. Eye
        d. Mantle
        e. Mouth

15. Give severalcharacteristics shell-less
                              of         gastropods

16. Why is the mantlevividly coloredin nudibranchs?

17. How do nudibranchs and seaharesprotect themselvesand color all three

18. Give severalcharacteristics cephalopods.
                              of

19. Give the functionsofall the partsofthe squid and octopus.

20. Color all the partsofthe squid and octopus.
 6
                SANDVBEAGH
 GHARAGTERIZAtrT@N:


 Sandy beaches, t familiar sight along open coastlines,       support relatively few species, which, however, gen-
 form by the accumul ation of sand pzrticles , the prod-     erally occur in great numbers due to reduced com-
 duct of erosion, which have been carried and                petition between species. The waues bring a steady
 deposited by uaues. Moving water carries particles          source of fine organic matter (detritus) as well as such
 suspended in it, and the more rapid the water move-         larger pieces of organic debris, as loose seaweed and
ment, the larger the particles carried. When the water       dead fish. These materials provide a dependable food
slows down, the largest and most dense particles are         source for the marine organisms of the sandy shore .
the first to settle out. As the water becomes very still,
the tiniest particles settle out (sedimentation or depo-      Color each sandy-beach organlsm as lt ls men-
sition) and accumulate as mud or silt.                        tioned ln the text, colortng both the large and
   On the open coast, where the water is seldom com-          small lllustrations of the anlmals.
pletely quiet, the larger particles settle out to form        The sand craD usesthe waves in moving up and down
sand bottoms. A tvpical mainland beach is composed            the shore . It feeds by burrowing its posterior end into
of small particles and fine gravel of quartz and feld-        the sand and then unfurling its long ant€nnae into the
spar. The beachesof tropical islands are sometimes            overlving water to filter food from the wave back-
composed oferoded coral, and the black sandsofcer-            wash (see Plarc 29).
tain Hawaiian beachescame from the erosion of lava               The small (2.5 cm) wedge-shapedbean clam <tf east
florl's, fhe particles that tbrm these sandy- shores         coast beachesis a rapid burrower and rides the wavcs.
originate on the land surface and are carried into the       sta,vingin the area of greatest water movement, where
sea by rivers. bv wind, or are weathered from the
                                                             suspended food is most abundant.
shoreline bv the pounding u'aues.
                                                                T}re razor clam is found along the beaches of the
   Once a beach forms. it changes continuouslv;
                                                             Pacific Northwest near the low-tide line. Razor clams
through the seasons,    the u,At.,es
                                   constantlv rework the
                                                             thrive on surf-zone diatoms (microscopic plants) that
sand and reshape the beach.
                                                             bloom throughout spring and summer. Anyone who
                                                             has pursued these delectable clams can tell you of
Color the illustrations   of the sandy beach,                their burrowing speed.
shown  in spring, summer, fall, and wlnter. The                 Like the raz or clam, the bri st Ie u)oftn, a scavenging
curved arrows in the fall illustration represent            polychaete, remains in the lower zone of the beach
the wave-driven removal of sand from the berm.              and relies on its rapid burrowing to keep from being
During spring and summer, gentle waues deposft sand         washed away by the tide .
onto the beacb platfurm, forming a broad sandy slope            Beach hoppers live in burrows above the high-tide
or berm. The large u'aues of the first fall storm begin     line and emerge at night to feed on deposited drift
to remove sand from the beach rnd deposit it off-           algae. The predaceous roue beetle also lives above the
shore in ridges, called sandbars. The winter beach          high-tide line. It comes down onto the shore at night
may have nothing remaining but the rocky beach              in pursuit of the unwary beacb bopper.
platform (the eroded edge of the coastline) znd cob-            Another nocturnal carnivore is the gDosf crab of
blestones too large for the winter wAues to carry off.      tropical and semitropical sand beaches. These crabs
   The beach is obviously a rigorous environment, and       are highly tolerant to air exposure and live in burrows
organisms that live here must adapt to constantly           above the high-tide line.
shifting san d and waues. Successfulspeciesare able to          The suimrning crab and the barred surfpercb ride
ride the uaues and to burrow deep into the sand, or         in with the tide to feed on sand crabs and,other bur-
are able to reside just above the tide line. Sandy shores   rowing animals.
SANEVBEAGH.
    SPRING-                                                       sunffnnER*




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  7
  SUtsMDAL
         S@FrB@TT@NfiS

   Most of the ocean floor consists of soft sands and             plants living here are specialized benrhic (bottom
   muds. The distribution of soft bottom types is gener-          dwelling) diatoms that live on the surface of the
   ally controlled by the same factors that create the            mud. The animals here are divided into an epifauna,
   sandy beaches: water movement and the character of            living on the surface, and the infauna, which live in
  the materials held in suspension determine the type            the substratum.
  and composition of the bottom.                                     Residing fust below the low-tide line along rhe cen_
     Soft bottoms on the continental shelf are composed           tral California coast is the large (15 cm) pismo clam,
  mainly of inorganic materials washed from the land             Pismos live in clam beds and feed on the large amount
  by rivers, or carried away by wind. The shallow bot-           of suspended detritus in rhe surf zone. They depend
  tom closest to shore experiences the strongesr wave            on their heavy shells to keep them in place.
  action and water currents; these keep all but large and           Just beyond the surf zone, beds of the suspension_
 dense sediment particles in suspension.These parti-             feeding epifaunal pacific sand dollar may be found,
 cles settle out, forming near-shore sandv bottoms.              together with the scavenging elbow crab and bermit
 These same turbulent near-shore waters hold a large            crab. Predators such as the sand star and the moon
 amount of organic detritus in suspension.The faunas            snail occur here, feeding on the numerous species of
 of these sand bottoms are dominated by filter feeclers         filter-feeding clams. like the sea cockle. Other life
 and their predators,                                           forms include the pacific sanddab flatfish and the flat
    At greater depth or in sheltered arcas,\,1-arcrmor.e-       angel shark.
 ment is lesse ned, and the fine r suspended particles are         In deeper, calmer waters, latge aggregationsof brit-
 deposited. A gradient of soft botroms results, ranging        tle stars may be found swarming on the bottom, feed-
 from coarse sand near shore, to muds, composed of             ing on deposited material, or buried in the sediment,
 very fine silt and clay particles found offshore over         with only their arms protruding through the mud.
the continental shelf. As the water becomes calmer             Another spiny-skinned animal found here is the bur-
and the suspendedorganic detritus settles to the bot_          rowing heart urcbin, or sea porcupine, which ingests
tom, the fauna shifts from suspension, filter feeders,
                                         or                    sediment as it burrows, digesting the organic material
to deposit feeders, who feed on this material.                 contained therein.
    Bevond the continental shelf, the character of the             Worms are among the most abundant infaunal ani-
soft bottom reflects what lives and grows above it in         mals. Their sleek, elongated bodies are perfectly
the water column. Vast areas of deep ocean bottom             adapted for efficient burrowing in soft substrata.
consist of the skeletons of minute planltonic plants          Many types of worms are found within the soft sub-
and animals (diatoms, foraminiferans, and so on).             strata; some ingest the sediment as they burrow
which form muddy "oozes" many feet thick. Other               through it; others feed on detrital materal deposited
areasof the deep ocean bottom are covered q,ith red           on the surfacel some filter suspendedmaterials from
muds composed of clav particles that have settled out         the water above. Shown here is a robust (5-10.0 cm)
verv slowly.                                                 burrowing polychaete uorrn, a carnivorous scaven_
                                                             ger that re-burrows very rapidly if uncovered.
                                                                 Soft substrata are very monotonous, homogeneous
Color each of the animals as lt is mentloned ln
                                                             habitats that offer a Iimited number of kinds of places
the text. Color both the lllustratlons         of the        for plants and animals to live, and thus, these habitats
anlmal in lts envlronmental      position (at the top        house a limited number of kinds of organisms. How-
of the page) and the larger illustratlons below.
                                                             ever, individual members of the fauna can be ex_
The soft bottom does not offer suitable substratum for       remely abundant, and play important roles in marine
the attachment of large algae (seaweed),and the main         food webs.
SUBTTDAL
       S@ffi B@TT@NfiS.


                                 I
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                                               _
                                               -

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PAGilFOG
       SAND D@LLAR^              l
                              ' . .
SANDSTAR,
Nfi@@NSNAOL.     INFAUNA-
ELB@W  GRAB,     PrcNN@GLAAfi
SANDDAB,         SEAG@GKLE,
ANGELSHARK,      HEART URGHIN^
BRMTLESTAR.      P@LVGHAETE W@RNf,.
HERNflIT
       GRAB"     BRITTLESTARO
                  . l




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                                               . r
    22
    ftfi@LLUSGAN
               DIVERSWg
    [NTER[@R
           @FASHELL


   A common introduction to marine biology is through
                                                                      When the adductor muscles relax, the
   the diversity and beauty of sea shells. Alihough theie                                                         compressed
                                                                      part of the ligament expands, and the
   shells are interesting to collect and examine, the                                                         stretched upp.,
                                                                     part of the llgament contracts. This
   molluscs that once lived within are even more fascina_                                                       results in the
                                                                      ualues gaping open so the cram can extend
   ting. This plate provides an understanding of how                                                               itsfoot and
                                                                     sipbons.
   some molluscs are structured and how they function,
                                                                        Also visible in this cross_seLtionalview is
   using the clam called a cockle as an example.                                                                    the fleshv
                                                                     mantle which completely underlies the
                                                                                                                 ualue and is
                                                                     responsible for its secretion and maintenance.
     Start by coloring the shell interlor at the upper
     rtght. Use ltght colors for the shell and mantle.
                                                                       Color fl.e clam at the top of the page and
    On the empty right shell, or ttalue, shown here,                                                                    the inter_
                                                            is a       nal view of the clam at the bonom of tfr" page.
    peak where thc shell began its formarion. Called                                                                          Note
                                                            the        that some names refer to related structures
    beak, or umbo, of the ualue, this pe ak can be used                                                                    seen in
                                                            as a       ttre emp* shell. Amows that indicate
    reference ro indicate the dorsal side                                                                         the direction
                                                @ack) of the          of the feeding currenr (below the gills)
                                                                                                                      should be
    clam. Below and to the right of the umbo (as
                                                                      colored the same as the incurrent siptro., (I).
    picrured), is rhe binge ligament. Made of protein,                                                                      Those
                                                           this       ,rrrows above the gills should be colored
    compressible structure serves to connect the t,ctlues                                                               the same
                                                                     as the excurrent siphon(f).
    and functions in the opening antl closing of them
   Below and to the sidc of the ligantent area number
                                                             of      At rhe rop of the plate, the cockle is shown
   projections called hinge teeth, which fit inro                                                                        in a side
                                                          cor_       view with its incuttent and excur.rent
   responding recesses     (sockets;in the other ualue. This                                                        sipbons ex_
                                                                     tended from the posterior end, and is
   tooth and socket arrangementaiclsin the articulation                                                          largefoot ex-
                                                                     tended from the anrerior end. This is the
   of the ualues bv preventing one from riding over                                                               normal posi_
                                                           the       tion of a burrowed cockle while actiyely
   other. This is important in burron.ing. or when                                                                      pumping
                                                           the      water for feeding and respiration. The raOiat
   clam is being attacked by a predator. since a                                                                       ilOges oi
                                                      tighrlv       the outside of the shell add strength and
  closed shell is irs most effective defense.                                                                      help anchor
                                                                    the cockle in the sand.
      Also visible in the empty t,ahtea.re fbur oval muscle              The illustration of the cockle at the
  scars. These muscle scars a,rethe sites of                                                                    bottom of the
                                                 attachment         plare shows the right ualue with its
  <lf the adductor muscles, nhich pull                                                                      underlyin g man_
                                                 the rcrll,es       f/e removed to expose the internal
  togerher and hold them shut. and ot rhe pedal                                                             organs. Cut free
                                                       (foot)      from the left ualue, the large adductir
  rerracror muscles(not shown). The thin,                                                                          muscles ere
                                                curving line       clearly visible. It can also be seen how
 joining the two adductor muscle                                                                                the extended
                                         scars is called the       sipbons are continuous with the fleshy
 pallial line, an<lit marks the point                                                                            manile that
                                          where rhe fleshv         lines the inside of thesbe//. Note the large
 mantle attaches rc the sbell.                                                                                   bilobedgi/d
                                                                  the smaller tabiat patp, andthefoot beieath
                                                                                                                       theg*iilsi;.
                                                                  These gilk are coyered with microscopic,
 Color the slde vlew and the cross sectlon of                                                                           hairlike
                                                         the      processes called cilia (not shown),
 two valves on the left of the plate. In the                                                                wtrictr wave in
                                                     cross_       unison to create a current. The arrows indicate
 sectional vlew, the cut is made through a                                                                                the di-
                                                     slngle       rection of the water current. As water passes
adductor muscle. The vlsceral masJhas                                                                                  through
                                                      been        the giIK, small particles, such as phytlplankron,
removed. Also color the arrows that lndlcate                                                                                 are
                                                         the     filtered out and are carried towird-thi
dlrectlon the valves move as they close                                                                          mouth (not
                                                      upon       shown) on mucous strands by specialized
contractlon of the muscle.                                                                                           cilia. De_
                                                                 posited onto the labial patps, the particles
                                                                                                                    are sorted
Looking at the two twlues in the cross-sectional                 by size. Smaller particles are directed
                                                      view.                                                  to the mouth,
one can see that the adductor muscles and, the                   located beneath the labiat palp. Rejected,
                                                       liga_                                                       larger par_
ment have opposing roles. When rhe adductors                     ticles accumulate below the gil/s, near
                                                       con_                                                    the foot, and
tract and the ualuesare brought together, a portion              are periodicallv expelled
                                                          of
Iigament is compressed and a portion is itretched.
                                                                       'l




                                                *, INTERIOR A SHELL.
                                                          OF

   G@GKLE-

                      \ r l




YALVE^
Uftfits@'
HflNGE LIGAMNENTb
HINGE  TEETH'
ADDUGT"   MUSG.  SGAR-
PEDALRETRAGT      SGAR'
PALLIAL  LilNE--




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                  \




              ANliluif-iL.
   ANITLEATAG HN,Lr\-l
 nfi             E
     AEEUGT@R NMUSGTE
              NNANTTE-
               SIPHON
      ilNGURREDNT
     EXGURRENT USIPHON        I t i ^ \ /   1

                                F,L.- -
                    GilLtS,
             iJAtsIALPAL-'
 23
                      THE
            DIVERSffiTB BIVALVES
 ftfi@LLUSGAN



  Variations in the structure and shape of bivalve                for deposited organic matter. The clam is named
                                                                  "bent-nosed"
 molluscs reflect evolutionary adaptations to different                                     for the noticeable curye in the posterior
 environments. Most malacologists (scientists who                region of its sbell. The clam lies in the sediment on its
 study molluscs) concur that the bivalve group evolved           left side with its bent-nosed posterior curved upward,
 from organisms originally adapted to living in soft             and its incunent sipbon extended beyond the muddy
 sediments, such as sand or mud. and that some secon-            surface. Food is sucked up through the incurrent
 darily took up existence on top of the substratum. The          siphon, carried into the mantle cavity, and collected
 discussion that follows includes three soft-substratum          on the gills (nor shown). Unlike its filter-feeding
 dwellers (members of the infauna) - the cockle, the             cousins who can remain relatively stationarl' as the
 softshell clam, and the bent-nosed clam; and two bi-            water brings their food to them. the deposit-teeding
 valves, the mussel and the scallop, that have adapted           bent-nosed clam soon depletes its food supph.in an
 to living on top of the substratum (epifauna).                  area and must move through the sediment to a ne$.
                                                                position. To facilitate this movement, the bent-nosed
Color separately the parts of each bivalve as the               clam is verv thin and possessesa broad. thin. ancl
animal is dlscussed in the text. Use a color for                maneuverable digging foot.
the shells light enough that the texture of the                     The edible mussel lives on the substratum attached
surface will show. Use a light color for the                    to pier pilings or rocks in the intertidal and shalloq.
                                   "eyes" with                  subtidal zones. It often occurs in large aggregations
scallop's mantle and then dot the               a
contrasting darker color.                                       c a i l c d r . r r u s s c l u n t p s .A t t e c h m e n tt o t h e s u b s t r a t u mi s
  The cockle is fbund living very' close to the surfacc,        by' means of special byssal threads, secreted as a liquid
 primarilv in sandv substrata. Its siphons are verv             from a gland near thefoot. The tbreads harden upon
 short; the incurrent and excurrent sipbons face               contact with the water, serving to hold the mussel in
                                                               position. The mussel lacks large protruding siphons,
 slighttv different directions to insure that the same
 water is not refiltered. Becausethe cockle lives so           and instead needs only a small ruffled area at its
 close to the surface, it is often exposed or dislodged        posterior end in order to direct the inflow and
                                    's                         outflow of water current for its filter feeding.
 bY wate r moyement. The cockle large diggingfoot is
 extremell' useful in reburrow'ing and escaping from               The scallop has developed adaptations appropriate
 predators.                                                    to its motile existence. The scallop is a filter feeder
     The softshell clam lives t.vpicallvin l'er,vsoft sandy    that lir-es on the sediment surface, completely unat-
  mud, where it burrows ver,vdeeplv. For filter feeding,      rached ro anv substratum.It needs neither siphons for
  it haselongate<l sipbons that enableit to reach bevond      feeding. nor a foot for digging. Ir has rows of "eyes"
 the surface,into the water current. As the clam grows        along the edge of the mantle that can detect shadows
 larger. it burron's deeper. and its siphons lengthen ac-     and movement and aid in avoiding predators. The
cordinglv. The softshell clam is rarelv dislodged from        e-l,es    ma)' be blue, red, gold, or other colors. depend-
 its deep burrow; therefore its need for rapid burrow-        ing on species. Along the mantle edge are mantle
 ing abilitv is much lessthan that of the cockle, and its     tentacles, which are sensitive to touch and contain
                                                              cells sensiriveto chemical information (chemorecep-
foot is much smaller.
     The bent-nosed clam is nof a filter feeder, but a        tors). These aid the scallop in perceiving its environ-
deposit feeder, using its long. maneuverable incur-           ment as it swims through the water bv clapping its
 rent sipbon to probe along the surface of the sediment       valves together (see Plate 86).




                                                                                                          r:atr+l'ra*.f.p_4!
     THEtsIVALVES.


               NfiUSSEL-




                                                                   SGALLO.P.




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                                                 i rl G,U        F e. .
                                                 EXGUFJ NT iSI }i .'',}!
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                                                 FO@T.
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                               GtANI -
      24
      ftfiOLLUSGAN
                 D[VERSffifs
      SHELLEDGASTR@P@DS

     The gastropods (Class Gastropoda) are the largest
                                                                                                       tenacity and remain securely fastened against
     class of molluscs; 15.000 fossil forms are identified.                                                                                                                       strong
                                                                                                       waves and most predators.
     and existing speciesnumber well over
                                            1r,000.                                                        The abalone has a pair of sensory tentacles and,
                                                                                                                                                                                        a,
                                                                                                       large mouth. Around thefoot of the abalone is
    Color the lower empty shell of the tullp snail                                                                                                                               a man-
                                                                                                      tle from which the epipodial tentacles protrude
    and use a light color for the body whorl.                                                                                                                                        . If
                                                                                                      the epipodial tentacles aie touched, the mantle
                                                                                                                                                                                      re_
    Most gastropod shells are built as a series of spirals,                                           tracts and a strong muscular contraction of the
    called whorls. The tip, or apex, of the shell, is                                                                                                                              foot
                                                         the                                          brings the shell down tightlv against the rock surface
                                                                                                                                                                                        .
    smallest uthorl laid down bv the snail in the earlv part                                             The abalone shell, measuring up to
                                                                                                                                                                        -i-.5 centi_
   of its life. As the snail grows, it lavs don,n rhe                                                meters in some species,has several openings through
                                                          in_
   termediate u,borls I'hich form the spire of the                                                   n'hich the excurrent respiratort. $.ater flows.
                                                       shell.                                                                                                                    Theie
   The final large spiral is the boctl,uthorl, rerminaring                                           excurrent openings also carrv out the w.aste
                                                           ar                                                                                                               products
   the aperture or opening. Thr- aperture is elongated                                               of digestion and e_rcre            tion and serve as the exit for ser
   into an anterior notch or sipbotral cannl, which                                                  c e l l s w h e n t h e a b a l o n es p a w n s ( s e ep l a t e t r + ) .
                                                        har_
   bors the incurrent respiraton. sipbon in the lir.ing
   snail.                                                                                            Color the cowry and the moon snail as
                                                                                                                                                                                    they are
                                                                                                     discussed ln the text.
    Color the illustration of the livins tulip                                                       Some of the most beautifullvparterned
                                                                                        snail.                                                                                     shells:rrr
    Lse a dark color lor rhe e1.es.                                                                  rhosc of the cownes, fbund in tropical
                                                                                                                                                                                    and sub-
   T h e t u l i p s n a i lp o s s e s s ea t < t u g h p r o t e i n a c e o u s
                                              s             .                                        tropical oceans. The cowry shell has a glossr,.
                                                                                         or.al-                                                                                            pol-
   shaped structure callecl the operculum, u.hich                                                   ished appearance.which is maintained br.the
                                                                                       is car_                                                                                       cow.rr.,s
   ried on its broad foot and is used to shut                                                       a b i l i t v t o c o m p l e t e l l e n c a s ei t s s h e l l w i r f r i t s
                                                                                   the snail                                                                                         *onitr,.
   snuglv into its shell. Vhen disrurbecl. he rulip                     t                           The two large mantle lobes can be drawn up
                                                                                         snail                                                                                      the sides
  rerracrs into its shell bl. first pulling in its bead,                                            of the shell to meet at the dorsal midline,
                                                                                         then                                                                                     or can be
   itsfoot, q'ith the opercttlunt brought in last                                                   completely q'ithdraw.n inro the shell. The mantle.
                                                                                 to seal off
  the shell.                                                                                        s h o w . ni n t h e i l l u s t r a t i o n o n l v p a r t i a l l v c o v e r i n g
                                                                                                                                                                                           thc
      Projecting anteriorlv is the elongarcd siphon                                                shell, is often brightly colored and patternecl
                                                                                         use<l                                                                                            ancl
  to carry e'ater to the gills (not show.nl for respiration.                                       sometrmes studded with small fleshv projections
  Special chemosensorv organs are located                                                          c a l l e d p a p i l l a e( n o t s h o s . n )
                                                                                  near the
 gills. The tentqcles are chemosensor\-                                                                The cowrv moves on its
                                                                            and touch_                                                           foot, probing wirh its ,err-
 s e n s i t i v e t h e e , ' e sa r e l i g h r - s e n s i t i r . e n t l
                 l                                                    a                            tqcles ltnd e,),es,taking in the respiritorv
                                                                              can detect                                                                                             current
 mot'ement.                                                                                       through its short funne l-like sipbon. The cowrl,
                                                                                                                                                                                        t-eeds
     Tulip snails are predatorv molluscs. feeding                                                 on small bottom-dwelling invertebrates such
                                                                                          on                                                                                        as com-
 o t h e r m < t l l u s c sp a r t i c u l a r l v o n b i v a l v e s . t h e
                              .                                                                   pound sea squirts and dead animals.
                                                                                      tulips
 r e a c h a l e n g t h o f l 0 c c n t i m e t e r sa n d a r e                                     The coq'rv shell grows up and over itself, so
                                                                              commonlv                                                                                                that in
 found in the Gulf of llexico and along                                                           the adult animal shell only the bod1, utborl is
                                                                        the southern                                                                                                 visible.
 c<tast the United Stares.
          of                                                                                     Cowrv speciesrange in size from 6 to 150 millimerers.
                                                                                                      The moon snail lives on the mud and sancl
                                                                                                                                                                                       flats,
Color the two illustratlons of the abalone.                                                      whe re a very largefoot aids its move me nt
                                                                                                                                                                           through the
The abalone is a large herbivore common                                                          soft subsrrara.            I_ocomotionis further aided by tn7pro-
                                                                                    to rhe      podium, an extension of thefoot that
Pacific coast of North America. The abalone                                                                                                                        servesas a plorl.
                                                                                  lives in
shallow rocky areasof considerables,ave action.                                                  to dig forward through the mud. The propodium
                                                                                        and                                                                                               has
the flar shell shape offers little resistance                                                   a flap that extends to cover the head of the
                                                                                ro E.arer                                                                                     snait. pro_
movement. The broad, flat bod1, u,borl terminates                                               viding protection and leaving only the sipbonancl
                                                                                          in                                                                                             the
an aperture that is as large as the u,borl itself.                                              tentaclesexposed as the snail travels through
                                                                                The /oor                                                                                         the sancl
of the abalone completelv fills the aperrure                                                    and mud. Note the spire and bod_y                           u,borl iri the moon
                                                                               . Because
of the size and rremendous surface irea of                                                      s n a i l s h e l l . T h e s n a i l p r e v s o n b i v a l r - em o l l u s c s
                                                                                thefoot,                                                                                                ancl
the abalone can grip the substratum q.ith                                                       other gastropods.
                                                                                 amaztng
 SHELLEE
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The shellless gastropods (sea slugs) are a group of         tory surface, and inside each is a glandular digestive
marine organisms that have shed the passive defenses        lobe. The cerata m y also contain specialized
of the shell and operculum and instead have devel-          cnidosacs in which are located undischarged nemato-
oped complex chemical and biological defenses to            cysts taken from their coelenterate prey. (Coelenter-
ward off their predators. They have adapted vividly         ates are alternately termed cnidarians.) Defensive
colored warning patterns and are sometimes referred         mechanisms present in some species include poison
      "butterflies                                          glands, prickly bundles of calcareousspicules (sharp-
to as              ofthe sea." Illustrated and discussed
here are two nudibranch sea slugs and the closely          pointed structures of calcium carbonate), or noxious
related sea hare.                                          mucous secretions,
                                                              Like the dorid, the aeolid has a pair of rbinopbores;
Begin by coloring        the dorld nudlbranch         as   it also possesses           pairs of elongated oral tentacles end,
described below. If you wish, color the encrust-           propodial tentacles located at the front of rhe foot.
lng sponge, on whlch the dorld is feeding, pur-            These additional sensory structures aid the aeolid in
ple or red.                                                finding and attacking its coelenterateprev.
Dorid nudibranchs dwell in rocky intertidal zones             The aeolid feeds primarih'on hvdroid colonies. Irs
throughout the world. and are common along the             elongated bodv and long narro*' foot (i cm) are
Pacific coast of North Ame rica. I'he spotted nutntle oi   a d a p t c d r o c l i n g i n g o n t h e e r e c r t r e c - l i k eh v d r o i c l .
the dorid covers the entire dorsal surface and hangs          Aeolid nudibranchs are seasonall.v                         common on the
down over the foot. The mantle surface of manv             Pacific coast of the United States,and occur both in
dorids is brilliantly colored or patterned and is          the "ocky intertidal zone and around floats and piers
thought to act in warning predators of the dorid's         in quiet harbors and bays.
unpleasant taste. In a few casesthe color matches the
background on which the animal feeds. This dorid           Now color the sea hare. Note that the parapo-
nudibranch is grey or light brown with dark bros'n or      dium (Bt) is an extension of the foot and receives
black spots. The average size is 7,5 centimeters and       the same color. You may wlsh to color the algae
the large, broadfoot and flattened bodv are adapted        green or red.
for feeding on its sole pre_y- the cncrusting sponge.      The sea hare. a close relative of the nudibranch. is
  A circlet of gill plumes protrudes from the dorsal       named for its large, rabbit ear-like oral tentacles and,
surface and is capable of complete retraction into a       its voracious, herbivorous appetite. It is among the
special pocket. A pair of dorsal chemosensory ten-         largest of the sea slugsl some species reach 40 cen-
tacles, the rbinophores, can also be retracted into the    timeters in length and may weigh up to 2 kilograms
special pocket structures.                                 (about 5 pounds).
                                                              The seahare possesses pair of rbinophores; its gill
                                                                                      a
Now. color the aeolld nudlbranch        as descrlbed       is covered by the mantle. The foot has two broad
below.                                                     *'ing-like flaps called parapodia, which can be fold-
The dorsal ornamentation of the dorid pales in com-        ed over its back or flap to create a respiratory current
parison with that of the aeolid nudibranch. The aeolid     over the gills.
has clusters of elongated dorsal structures called            Defensive adaptations of the sea hare include its
cerata, often brightly colored with vivid contrasts,       secretion of a distasteful milkl' substance, and the
and these are thought to draw attention away from          glandular ejection of a vivid purple dye. In their
the unprotected rhinophores a.nd oral tentacles. If        mantles, sea hares store noxious organic compounds,
damaged or removed by predators, the cerata are            garnered from algae, that further deter predators.
quicklv regenerated. The cerata function as a respira-
                         GASTROPOES.
                SHELT"LESS
i
                MANTlLB
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                                                       D@R[D
                                                           NUDIBRANGH-
                                                       /al,l     I    T;ln nnni.rr=
                                                       t(ql ll   tl   l2ll    l l l l l i V , { l l =-
                                                                      u   Jv,_,J-,d_

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                                                      ^r.:- rJL:/ Ju.:, dlULULll/t[UfUu                        ro*
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                                                                  TENTAGIE-
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                                 SEA HARE-                                                                           1


                               PARAP@EilUftfi,
   27
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 The squid and the octopus are two highly developed                                          poison. The beak is located in the center of the circle
 members of the class Cephalopoda. tVhile the cham-                                          of arms, protruding from the mouth; it cuts the prey
 bered nautilus relies for buoyancy on the ancestral                                         into small pieces that are then carried into the mouth
 molluscan shell, the squid's thin shell is located                                         by the radula (not shown).
 within the mantle and is useful only for muscle attach-                                        Located on the anns ^re stdked, adhesive discs, or
 m€nt; the octopus has lost its shell entirely.                                             suchers (see circled enlargement), which in some
                                                                                            species are reinforced by hornv rings or hooks. Con-
 Begin by coloring                 the large illustration                  of the           traction of the muscles attached to eachsucker cr€ates
 squld.                                                                                     suction when the suckerscome in contact with some-
 The squid swims by forcing water out thefunnel, ina                                        thing solid. The tentacles, twice as long as the arms,
 jet propulsion fashion. This, with its tapered, stream-                                    hzve suckers only on their flattened ends.
 lined bod.y and the broad triangular fins used for stabi-
 lization, makes the squid a highlv effective swimmer.                                     Color both lllustrations of the octopus. Note that
 Normallv, the squid swims backward. Squidsma1'also                                        the beak is not shown here. Also color the en-
 swim forward, bl' directing the funnel posteriorlv.                                       largement of the suckers, showing thelr shape
 and are capable of hovering motionless in the wate r.                                     and relative slze.
 O v e r s h o r t d i s t a n c e s .s q u i d s a r e a m o n g r h e m o s t             The octopus does not normailv swim about in the
 rapid mor-ing of all nrarinc organrsms. Largc squids                                       $ - a t e . I t w i l l s n ' i m , h o n ' ev e r , i f t h r e a t e n e d .I t s w i m s
                                                                                                    r
 c a n a t t a i n s p e e d so f 2 4 - 3 2 k i l o m e t e r s ( 1 5 - 2 0 m i l e s )     n'ith its soft bag-like body held in the direction of
per hour.                                                                                  movement. and its bead and eight arms trailing be-
    The muscular mantle of the squid and the mantle                                        hind. Thep nnel is dire cted rearward and the ocropus
cavity it houses are strengthened internalh' by plates                                     moves in tvpical cephalopod fashion, propelled br.
of cartilagein the body' wall and bv the remnant of the                                    forcing a jet of water out the funnel.The octopus
shell (called the pen. not shown). The eight arms and                                      lacks the streamlining that makes the squid such a suc-
two tentacles can be held motionless in front of the                                       cessful swimmer; it prefers to remain in contact w.ith
squid's bead to aid in streamlining. Thefunnel is both                                     a solid srrucrure, pulling itself along using the suckers
moveable and muscular, so that in swimming, rhe                                           on its arms.
opening (lumen; can be constricted, therebv increas-                                          In most octopus speciesthere are about Z4Osuckers
ing the pressure of the water forced out of it bl' the                                    on each arm, usuallv arranged in double rows. The
contraction of the mantle cavity.                                                         suchers lack the stalk, the horn_vrims and the hooks
                                                                                          possessed the squid. Octopus suckers varv in size
                                                                                                            by
Color the enlargment                    of the front view of the                          from a few millimeters to 7 centimeters in diameter.
squld and the drawlng                   of the beak.                                      A sucker 2 centimeters in diameter requires a pull of
Its swimming abilitv. coupled with its image-forming                                      six ounces to break its hold, so one can imagine the
eyes, gives the squid a tremendous advantage as a                                         strength it w'ould take to break a hold of tw.o thousand
predator. It can swim into a school of fish and quickly                                   suckers!
capture one with its long sucker-tippecl tentacles. The                                       The octopus generallv is a solitary dweller and
fish is dispatched with a bite behind the head from the                                   seeks shelter or a permanent den in a cave or under
beak of the squid - accompanied by an injection of                                        rocks.
                                           '1




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