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					Chapter 33 Notes

 Invertebrates
Concept 33.1
Phylum porifera:
 - asymmetric
 - ex. sponges
 - sessile adults, larva may swim
 - have no nerves or muscles; individual
 cells can sense and react to
 environmental changes
Concept 33.1
 - filter-feeders; choanocytes, or collar
 cells, ingest food filtered through the
 sponge
 - most are hermaphrodites
Concept 33.1
Concept 33.1
Concept 33.2
Phylum Cnidaria:
 - radial symmetry
 - ex. jellyfish, hydra, sea anemones,
 coral
 - have stinging cells called nematocysts
 or cnidocysts; eject a barbed thread
 - contain a gastrovascular cavity; single
 opening
Concept 33.2
Concept 33.2
 - sessile forms are called polyp; free-
 floating are called medusa
 - diploblastic (epidermis and
 gastrodermis); between layers is the
 mesogloea
Concept 33.2
Concept 33.2
Concept 33.2
Concept 33.2
There are 3 classes of Cnidarians:
Hydrozoa:
 - ex. hydra, Portuguese man-of-war
 - most marine
 - both polyp and medusa stages; polyp
 is often colonial
Concept 33.2
Scyphozoa:
 - ex. jellies
 - all marine
 - polyp stage is reduced
 - free-swimming
Concept 33.2
Concept 33.2
Anthozoa:
 - ex. sea anemones, coral
 - all marine
 - medusa stage absent
 - sessile
Concept 33.2
Concept 33.2
Phylum Ctenophora:
 - means “comb-bearer” for the eight
 rows of fused cilia
 - ex. comb jellies
 - tentacles contain colloblasts to
 capture prey
Concept 33.3
Phylum Platyhelminthes:
 - ex. Flatworms, flukes, tapeworms
 - bilateral symmetry
 - unsegmented
 - triploblastic; acoelomates (no body
 cavity)
Concept 33.3
Class Turbellaria:
  - flatworms
  - free-living
  - rely on diffusion for movement of
  food, oxygen, and waste
  - asexual and sexual reproduction; can
  regenerate lost parts
Concept 33.3
Concept 33.3
Concept 33.3
Class Trematoda:
  - ex. blood flukes, liver flukes
  - all parasitic: feed on veins/organs of
  host
  - hermaphroditic
Concept 33.3
Class Cestoidea:
  - ex. tapeworms
  - all are parasites
  - attach to intestinal wall with scolex
  and absorb food from host
Concept 33.3
Concept 33.3
Phylum Rotifera:
 - psuedocoelomates
 - freshwater
 - complete digestive tract
 - fluid in psuedocoelom acts as a
 hydrostatic skeleton
Concept 33.3
Concept 33.3
Phylum Nematoda:
 - ex. roundworms
 - complete digestive system and closed
 circulatory system: blood is contained in
 vessels
 - decomposers and parasites
Concept 33.4
Phylum Mollusca:
 - ex. snails, slugs, clams, squids,
 octopuses
 - body consists of three parts: foot,
 visceral mass, mantle
 - open circulatory system
 - gas exchange is via gills, lungs, or the
 body surface (diffusion)
Concept 33.4
Concept 33.4
Class Polyplacophora:
  - ex. chitons
  - use foot to cling to rocks
  - simple nervous system and sense
  organs
Concept 33.4
Concept 33.4
Class Gastropoda:
  - “stomach-foot”
  - ex. snails and slugs
  - torsion: uneven growth in the
  visceral mass; rotates 180 degrees
  - exchange gases via gills; use mantle
  cavity
Concept 33.4
Concept 33.4
Class Bivalvia:
  - “hatchet-foot”
  - ex. clams, oysters, mussels
  - foot used for motility or anchorage
  - suspension feeders
  - no distinct head
Concept 33.4
Concept 33.4
Class Cephalopoda:
  - “head-foot”
  - ex. squid and octopus
  - carnivores; beak-like jaw to crush prey
  - have chromatophores to allow them
  to change colors
  - shell is reduced or absent
Concept 33.4
Concept 33.5
Phylum Annelida:
 - ex. earthworms, leeches
 - all are segmented
 - setae project from cuticle
 - closed circulatory system; aortic
 arches
Concept 33.5
 - developed nervous system with two
 ventral, solid nerve cords and cerebral
 ganglia
 - complete digestive system: mouth-
 crop-gizzard-intestine-anus
 - sexual and asexual reproduction
 - tactile organs, chemoreceptors,
 balance receptors, and photoreceptors
Concept 33.5
Concept 33.5
Concept 33.5
Class Oligochaeta:
  - ex. earthworm
  - all have setae
  - help aerate soil and cycle nutrients
Concept 33.5
Class Hirudinea:
  - ex. leeches
  - mostly freshwater
  - either carnivorous or parasitic
Protosomia
Class Polychaeta:
  - primarily marine
  - parapodia with bristles; can be used
  for locomotion and gas exchange
  - largest class
Protosomia

				
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posted:11/30/2011
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