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What type of group are invertebrates?
Paraphyletic
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How do sponges feed?
- Suspension feeders
- engulfed through phagocytosis
- choanocyte digests nutrients
- amoembocyte transport nutrients
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How do sponges reproduce?
- sequential hermaphroditism (born one sex but change at some point in life)
- sperm is a modified choanocyte
- egg is a modified amebocytes
- larva stage is ciliated
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Importance of Sponges
- filter feed and therefore clean water
- home for other organisms
- mutualism with single-celled algae
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Human uses for sponges
- antibiotics and anticancer drugs
- bath and art sponges
- (most organisms don't eat, toxic)
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Characteristic of Phylum Cnidaria (jellyfish, hydras, sea anemones and coral)
- Eumetazoa (includes most animals other than sponges): have true differentiated tissues
- -diploblastic= two layers (endo & ecto)
- -organs
- Mostly radially symmetrical
- Almost entirely marine
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What are the two body forms of Cnidarians? (jelly fish, sea anemones etc.)
- Polyp: oral end facing upwards and attached to substrate (sea anemones & hydra)
- Medusa: oral end downwards, move freely through water (jellyfish)
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How do Cnidarians capture prey?
Use Cnida (within cnidocyte, usually a nematocyst) for prey and capture
when cnidocyte touches something cnida shoots out and captures/poisons prey
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How are classes of Cnidaria differentiated?
Dominant body form
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What is the most common class of Cnidaria?
Class Hydrozoa (poly and medusa in life cycle)
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Hydrozoa reproduction
alternate between sexual and asexual, but always remain diploid
- Polyp-reproduce asexually through budding
- Medusa-produced asexually but reproduce sexually, larva returns to polyp
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What form is class Scyphozoa?
Mainly medusa (jellyfish)
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What form is class Cubozoa?
- medusa dominant (box jellies)
- extremely toxic
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What form is class Anthozoa?
- only polyps
- single-sea anemones
- colonial-corals
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ecology of cnidarians
- predatory (of zooplankton)
- house symbiotic algae
- produce dangerous toxins
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Importance of cnidarians
- reefs provide food and shelter for marine species
- human: tourism, fishing and aquarium trade
- coral bleaching signifies ecological meltdown
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Features of clade bilateria
- bilateral symmetry
- Differentiation of head region:
- -anterior concentration of neural ganglia (brain)
- -reduced in sedentary animals
- triploblastic
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Features of Phylum Acoela ("worms")
- mostly marine worms
- no body cavity (acoelomate)
- minimal cephalization (no brain)
- use endocellular digestion since they lack anus and gut cavity
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