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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