Cabrillo Aquarium Exercise The Invertebrates

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					Cabrillo Aquarium Exercise: The Invertebrates
Directions to the Cabrillo Marine Aquarium, San Pedro: From PIERCE take the San Diego Freeway south to the Harbor (110) Freeway - San Pedro. Continue on the Harbor Freeway south, take the Catalina exit/Harbor Blvd (towards Vincent Thomas Bridge). Turn right at the end of the offramp and take Harbor Blvd. all the way to 22nd St. Turn right on 22nd and then left on Pacific Ave (second traffic light). Take Pacific Ave with Fort Mac Arthur on your left to 36th street. Turn left onto Stephen White Drive and follow curve to right to Cabrillo Beach. There is limited free parking along the street or pull into the lot at the Aquarium for hourly parking. Weekdays during the winter parking is (was?) free. The aquarium is open at 10am to 5 pm Tuesday though Sunday in September. Starting in October the hours are 12 - 5pm Tuesday through Friday and 10 am - 5 pm weekends. The aquarium is closed on Mondays. The number is 310/548-7562. What to do before going. Read over this exercise and look up each group of organisms in your text. By first reading and studying the organisms you will better benefit from the aquarium visit and be able to complete the exercise more quickly. What to do once you are there: On arrival obtain a Visitor=s Guide from the information desk. This has a map and a listing of the major exhibits. In the exercise that follows I reference the exhibit by its name in bold italics to make it easier for you to locate the information. For each of the organisms look at the exhibits indicated and list the genus of the organisms that belong to the group described after Aexamples:@. Breakfast/Lunch/Dinner. I recommend the Lighthouse Deli on the corner of Pacific Ave. and 39th St. Just 3 blocks toward the water past Stephen White Drive.


Sponges (Phylum Porifera) The body is covered with a perforated Askin@ (epidermis) and body penetrated by numerous small channels forming the body cavity (spongocoel). Channels lined with flagellated Acollar@ (choanocyte) cells. Feeding is accomplished by creating a current with flagellae (microscopic Awhips@) of collar cells that draws water in through skin and through channels where food is trapped by the collar cells. The prey is primarily phytoplankton, bacteria and detritus. Sponges are found mostly in dark areas: beneath rocks, and in caves due to poor ability to compete with faster growing alage for space. Exception is in the tropics where the grazing pressure from fishes on algae allows the less palatable sponges to persist in lighted areas. Animals That Look Like Plants, Filter Feeders - examples:

Jelly fish, Aemones, Corals, Sea fans (Phylum Coelenterata/Cnidaria) All have radial symmetry and possess primitive gut or gastrovascular cavity. Two body forms possible: medusa: swimming bell with tentacles on edges or margins of bell or polyp: benthic (attached) column with tentacles surrounding mouth, attaches with a bottom or pedal disc. Tentacles surround the mouth and are used for prey capture and defense. The stinging cells on the tentacles are called nematocysts and work even when the tentacles are detached from the animal (Stinging Tentacles) may form or of both medusae and polyps. Some attached (benthic) on hard bottoms (anemones, corals, sea fans), some anemones are infaunal (burrow into soft bottoms), jellyfish and most siphonophores are planktonic. Dispersal is by planktonic planula larva and medusae, budding for rapid exploitation of resource (space). Hydroids (Class Hydrozoa) Hydroids are small and soft bodied with multiple anemone-like polyps on a common branching structure - some eresmble feathers. They feed on microscopic plankton by passive suspension feeding. The siphonophores colonies of medusae and polyps together. At The Mercy of Currents - examples:

True Jelly Fish (Class Scyphozoa) The swimming bell or medusae dominant life phase with long feeding tentacles for prey capture. Moonjellies, Plankton - examples:

Sea Anemones, Hard and Soft Corals, Sea Pens, Sea Pansys (Class Anthozoa) All have are polyps attached to hard surfaces or burrowed into mud/sand. Solitary (anemones, cup-corals) and colonial forms (stony coral heads, branching corals) are common. The corals have a skeletal cup (theca) of either CaCO3 (stony corals) (House Builders) or softer


organic materials (sea fans). Many anemones and corals have microscopic lage, the zooxanthellae, which provide the animals with sugar for growth in exchange for a place to live and nutrients (above Plant-like Animals). A Mudflat Metropolis Plantlike Animals To left of Tidepool Animals (in chainlink enclosure) and in Territorial Fish Stinging Tentacles - examples:

Clams, Snails, Octopus, Chitons, Tusk Shells (Phylum Mollusca) The body can be separated into three component parts: (1) the foot: used for locomotion/attachment, can be extended from shell if present; (2) the visceral mass: contains the organs, located above (dorsal to) the foot; and (3) the mantle: skin (membrane) surrounding the visceral mass to form the mantle cavity, possesses glands with which to secrete the shell. Reproduce sexually with either separate sexes or hermaphroditically (have both male and female sex organs). Dispersed by a free swimming veliger larvae. There are six classes in total, althoug we will examine only five. Classes: Ampineura, (Monoplacophora), Scaphopoda, Pelecypoda, Gastropoda, Ceplalopoda Chitons (Class Amphineura) The shell consists of 8 articulating (jointed) plates held in place by a fleshy girdle. There is no distinct head, only a mouth. Locomotion is by a muscular foot. Mostly grazers that feed with a file-like radula. Across from Plantlike Animals in the display case beneath Seaweeds Borers on Rocky Shores - examples:

Snails, sea slugs, nudibranchs (Class Gastropoda) The snails have shells and distinct heads with Aeyes@ and tentacles. They may have gills or "lungs", but in the nudibranchs, which lack a shell, the gills are exposed on their dorsal surfaces (backs). In the sea slugs the shell is small and internal. All have a file-like toungue called a radula which used for either grazing algae or boring into shells of prey. Predators of Plantlike Animals Predatory Snails Bursa below Diets of Stars Seashore Vegetarians Meals in the Mud - examples:  archaeogastropods: (limpets and abalone) simple shell lacks spiral  neogastropods: spiral shells, many predators (welks)



sea slugs and nudibranchs: shell internal or lacking, gills in mantle fold or on dorsal surface, distastful and often with warning coloration, some incoorporate nematocysts from ingested cnidarians

Tooth or Tusk Shells (Class Scaphozoa) Note: may not be able to find Tusk -like shells of- live buried in sand/mud. -examples:

Clams, Oysters, Mussels, etc. (Class Pelecypoda/Bivalvia) Members of this group lack heads and the foot is adapted for digging into mud/sand in most. The shell composed of two hinged valves. The mantle may form a siphon or tube to surface in the infaunal species. Oysters and rock scallops cement one of the valves to a rock. Mussels attach to the surface of hard surfaces with a byssus or Abeard@. All are active suspension feeders. Pearls are formed when foreign objects are introduced between the shell and the mantle tissue. Buried Alive Animals That Bore - examples:  clams: burrow into substratum - mud to rock  oysters/scallops: one valve attached to substratum - large adductor muscles to hold valves closed


mussels: byssus to attach - ribbed with inflated shell to live on surface

* pholids: bore into hard substratum with acidic secretions and shell

Squid, Octopus, Cuttlefish, Nautilus (Class Cephalopoda) The cephalopods are highly motile and voracious predators that use tentacles and a powerful parrot-like beak to attack their prey. The body is a bag or tube that is inflated with water to form a hydrostatic skeleton, that is water under pressure like in a baloon. The head is surrounded by strong sucker covered tentacles. Movement by jetting action as water is shot out of the body cavity. All are capable of dramatic color change by use of special organs called chromatophores. Octopus have been shown to be capable of considerable learning. Octopus, Adaptable Cephalopods (across from Fish Divesrity) - examples: * octopus: use beak and/or drilling for prey capture  squid: swim with finlets and jetting


* nautaloids: chambered shell used for buoyancy control

Lobsters, Shrimps, Crabs, Barnacles, Sowbugs, Sand Crabs, etc. (Phylum Arthropods, Class Crustacea) All crustaceans have a hard external skeleton (exoskeleton) with jointed (articulated) legs, swimming appendages, and antennae. Mouth contains crushing plates or mandigble. Must shed skeleton to grow in a molting cycle. In most species the abdomen is straight, liek a shrimp, hoever in the crabs it is small and folded up underneath the thorax (chest-like area). Reproduce sexually with separate sexes, females hold eggs (brood) on abdomen until eggs hatch. Dispersal by several planktonic larval stages. Copepods (Subclass Copepoda) Small (1/4 inch) and shrimp-like with long antennae used for swimming. Planktonic grazers on phytoplankton; very abundant: lowest consumer on food chain of pelagic (water column). Some are parasitic on fish. To Left of Hunters of Rocky Shore, The Twilight Zone (across from Plankton) - examples:

Barnacles (Subclass Cirripedia) Described as "nothing more than a little shrimp-like animal standing on its head and kicking food into its mouth" The small organisms settle from plankton on their heads and cement to the substratum. They then secrete CaCO3 plates around the body to form familiar Ashell@. Active suspension feeder uses hair-like cirri on "legs" to filter planktonic food (Filter Feeders - External Filter and to left of Sandy Beach tank). Gregarious settlement important for survival and reproduction. They are simultaneous hermaphrodites practicing reciprocal insemination. Filter Feeders - examples:

Isopods, Pillbugs (Order Isopoda) Represented on land by Asow bugs, or pill bugs@. Most are small and scavange on dead organisms. A few are parasitic on fish and will readily clean the bones. To Left of Hunters of Rocky Shore - examples:

Amphipods (Order Amphipoda) Small (1/4 inch) shrimp-like creatures found in very large numbers in algae on the 5

bottom. Rise up in the water column at night to form the demersal zooplankton which are an important food of corals. They are also a large part of the diet of bottom Apicker@ fish. They also act something like like piranas in that they will clean the bones of a dead fish clean overnight. Life in Death To Left of Hunters of Rocky Shore - examples:

Euphausids, Krill (Order Euphausidacea) Shrimp-like creatures that are very abundant in areas of hogh productivity, especially in Antarctica. An important part of the diet of many baleen (suspension feeding ) whales. The Twiligth Zone (across from Plankton) - examples:

Shrimps (Suborder Natantia) A familiar form to all. These demersal creatures feed for the most part on bottom particulate detritus (pieces of decaying matter) which they pick up with their numerous clawed legs. The large abdomen coupled with the fan-like tail (telson) is used in a Atail flick) escape response from predators. In Octopus tank Cleaners of the Rocky Shore - Sensible Solutions Crustaceans - examples:

Suborder Reptantia The 1st pair of legs powerful chelipeds (claws) Lobster, Crayfish (Section Macrura) These elongate animals have very large abdomens for a strong escape response. They possess large claws (chelae) which along with the mandilbles are used to crush clams and snails. The spiny lobster lacks claws. Crustaceans - examples:

True Crabs (Section Bracyura) The body is wider than long and the abdomen is folded beneath. Large chelae (claws) are used to crush clams and snails, and in the swimming (blue) crabs, to cathc fish. To left of Hunters of the Rocky Shore - examples: 6

Sand Crabs, Hermit Crabs, Ghost Shrimp (Section Anomura) These egg-shaped relative of crabs have the abdomen flexed sometimes but not reduced in size. The sand crabs burrow into the sand and suspension feed (to left of Sandy Beach Wave tank)with their antennae while the hermit crabs occupy the shell of a snail (Sensible Solutions) and scavange on algae and detritus. Ghost shrimps form large burrows in muddy bottoms and deposit feed (Burrowers and Tubewellers). To left of Hunters of the Rocky Shore - example:

Sea Urchins, Sea Stars, Sea Cucumbers, Sea Lilies, Sand Dollars, Brittle Stars (Phylum Echinodermata) All of the echinoderm groups have a pentamerous (5-part) radial symmetry and all except the sea cucumbers have hard internal calcareous skeleton. The surface may have bumps or spines. Movement and prey capture for most is with the water-vascular system: a series of internally connected tubes that connect to sucker-like tube. Fertilization is by simultaneous release of sperm and eggs into the water, dispersal is by a planktonic pluteus larva. Sea Stars (Class Asteroidea) The body consists of a central disc with radiating arms or rays in multiples of 5. Tube feet project for movement and prey capture. One of two stomachs may be everted from the mouth to digest prey outside of the sea stars body (to left of Tidepool Animals). Sea stars locate prey by specialized tube feet at ends of rays to "smell" (chemoreception) slow moving and sessile prey (limpets, barnacles. Sea stars also have amazing regenerative abilities (Powers of Regeneration, next to Diets of Stars). Predatory Seastars - examples:

Brittle Stars (Class Ophiuroidea) The brittle stars have a central disc with thin arms that autotomize (break off) easily. They move away from light to the protection of crevices and undersides of rocks by negative phototaxis. Arms with fine spines are typical of suspension feeders; smooth arms typical of deposit feeders. Diets of Stars Nonpredatory Echinoderms - examples:

Sea Urchins, Heart Urchins, Sand Dollars) (Class Echinoidea) 7

The plates are fused to form a spherical to pancake-like shell or test; spines articulate and may be large. Movement is by either tube feet or by spines. These animals have well developed chemosensory ability and a specialized five-beak jaw called an Aristotle's lantern. Nonpredatory Echinoderms In Bed With Sand Dollars - examples:

Sea Cucumbers (Class Holothuroidea) This group has a leathery skin with very small skeletal plates. They lie on their sides or occupy holes in the substrate. The mouth is surrounded by feeding tentacles fow either scouping up sediment or suspenskion feeding. Many are have with toxic skin for defense. If disturbed will change shape and may eviscerate (spew guts out their mouth). Nonpredatory Echinoderms - examples: Sea Lilies (Class Crinoidea) Note: No examples This is the oldest and most primitive class of echinoderms. They have a stalk and they move and attach with numerous claw-like cirri. Several feathery appendages are directed upwards to suspension feed on plankton. - examples: