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29 Cards in this Set
- Front
- Back
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animal
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multicellular, heterotrophic eukaryotes that obtain nutrition by ingestion
--evolved from colonial flagellated protist about 700 mya |
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radial symmetry
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identical all around a central axis (sea anemone)
--sessile animals (stationary) |
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bilateral symmetry
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only one way to split into two equal halves--down the midline
--motile animals (mobile) |
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major events in animal evolution
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1. distinguishes sponges from all other animals based on structural complexity. sponges, though multicellular, lack the true tissues, such as nervous tissue, that characterize more complex animals
2. split based on body symmetry 3. evolution of body cavities 4. protostomes vs. deuterostomes |
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body cavity
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a fluid-filled space separating the digestive tract from the outer body wall
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protostomes vs deuterostomes
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-2 distinctively different ways the coelom is formed during embryonic development
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protostomes
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mullusks, annelids, and arthropods
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deuterostomes
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echinoderms and chordates
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invertebrates
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animals without backbones
95% of all known animal species are invertebrate4s |
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poriforans
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the sponges..sessile animals that appear so sedate to human eye that ancient greeks believed them to be plants
--body resembles sac with holes in it --flagellated cells lining central cavity trap and engulf bacteria |
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Cnidarians
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jellyfish, corals, and anemones
--characterized by the presence of body tissues as well as by radial symmetry and tentacles with stinging cells |
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gastrovascular cavity
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basic body plan of of a cnidarian is a sac with a central digestive compartment
--tentacles with cnidocytes --polyps and medusas |
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polyp
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one of two types of cnidarian body forms; a columnar, hydra-like body
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medusas
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one of two types of cnidarian body forms; an umbrella-like body form; also called a jelly
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flatworms
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phylum platyhelminthes
1. simplest bilaterally symmetrical animals 2. digestive tract with single opening 3. some are parasites (fluke and tapeworms) |
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nematodes
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roundworms get common name from their cylindrical body, usually tapered at both ends
--important as decomposers --90,000 species --parasites--hookworms, pinworms, trichina worms |
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complete digestive tract
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a digestive tube with two openings, a mouth and anus
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pseudocoelom
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a body cavity not completely lined by mesoderm-derived tissue
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mollusks
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protostomes with true coelom
-soft-bodied animals but more are protected by a hard shell |
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3 major groups of mollusks
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1. gastropods
2. bivalves 3. cephalopods |
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gastropods
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snails and slugs
protected by a single spiraled shell into which the animal can retreat when threatened |
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bivalves
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clams, oysters, mussels
have shells divided into two halves hinged together most are sedentary, living in sand or mud in marine and freshwater environments |
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cephalopods
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squids and octopuses
built for speed and agility some have large, heavy shells, but in most the shell is small and internal (squids), or missing altogether (octopuses) |
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annelids
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earthworms and leeches
worms with body segmentation coelom divided into segements by septa |
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segmentation
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subdivision of the body along its length into a series of repeated segments. looks like a set of fused rings
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arthropods
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most diverse and successful animal group
named for jointed appendages -grabs, lobsters, spiders, scorpions, grasshoppers, moths |
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reasons for success of arthropods
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1. segmentation and specialization
2. hard exoskeleton (chitin) 3. jointed appendages |
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metamorphosis of arthropods
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larva, pupa, then adult
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major groups of arthropods
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1. arachnids (spiders, mites)
2. crustaceans (lobsters, shrimp, crabs) 3. insects (beetles, flies, bees, wasps, ants) |
