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55 Cards in this Set
- Front
- Back
How many animal species are there?
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1.3 million species described, but 10-20 or 100-200 million total
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How do animals differ from plants?
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1. Animals differ from plants and fungi in their mode of nutrition.
Plants are autotrophic and derive nutrition through photosynthesis. Fungi release exoenzymes that digest food outside their bodies. Animals eat other living organisms or nonliving organic materials use enzymes to digest food after they’ve ingested it. 2. Animals are multicellular (like plants and fungi) but they lack cell walls for support. Instead, they’re held together by structural proteins like collagen. 3. Animals have specialized cell types organized in into epithelial tissues. 4. Animals have two specialized cell types not seen in other multicelluar organisms, muscles & nerve cells. 5. Most animals reproduce sexually and the diploid stage dominates the life cycle (there is no haploid multicellular gametophyte). 6. In most species, a small motile sperm fertilizes a large nonmotile egg, producing a zygote. |
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Heterotrophs
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Animals are heterotrophs, and are unable to synthesize organic, carbon based compounds independently from the inorganic environment's sources (e.g. Animalia, unlike Plantae, cannot photosynthesize) and therefore must obtain their nutrition from another heterotroph or an autotroph.
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Cleavage
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A succession of mitotic divisions
without cell growth between divisions |
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Blastula
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Multicellar stage resulting from many cleavages. The blastula of many animals is a hollow ball of cells.
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Gastrulation
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Following blastula stage, one end of the embryo folds in, expands, and eventually fills the blastocoel.
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Blastocoel
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Inside of a hollow blastula
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Archenteron
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The hollow center formed by gastrulation, the archenteron opens to the outside through the blastopore
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Blastopore
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Opening of the archenteron, forms the mouth or the anus when developing into an animal.
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Endoderm
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Eventually forms the lining of the digestive tract, lines inside of archenteron. Ectoderm lines outside of cleaved cell.
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Spiral Cleavage
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Planes of cell division (cleavage) are diagonal to the vertical axis of the embryo
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Radial Cleavage
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Planes of cell division (cleavage) line up
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Coelom
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The usually epithelial-lined space between the body wall and the digestive tract
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Protostomal Development
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Spiral and determinate, schizocoelous, mouth from
blastopore |
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Deuterostomal Development
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Radial and indeterminate, enterocoelous, anus from blastopore
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Schizocoelous
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Solid masses of mesoderm split and form coelom- Protosomes
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Enterocoelous
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Folds of archenteron form coelom- Deuterostomes
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Acoelomates
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Lack a body cavity between
the digestive cavity and the outer body wall |
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Pseudocoelomates
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Have a body cavity only
partially lined (by tissue derived from mesoderm) |
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Coelomates
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Have a body cavity
completely lined (by tissue derived from mesoderm) |
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Diploblastic
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Animals have only two layers: ectoderm and endoderm
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Triploblastic
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Animals have three layers: ectoderm, endoderm and mesoderm
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Asymmetrical
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Have no real symmetry, like sponges
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Radial symmetry
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They have a top and bottom, but no front or rear, and no left and right sides, like sea anemones
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Bilateral symmetry
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They have a top and bottom, a
front and rear, and left and right sides, like humans |
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Animals in general
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•heterotrophs
•multi-cellular •specialized tissues (including muscles and nerve cells) •sexual reproduction with a dominant diploid stage •small motile sperm and large non-motile eggs |
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What is sister to Fungi + Animalia + Choanoflagellates?
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Amoebozoa, common ancestor like an amoeba?
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Common ancestor of Animalia and Choanoflagellates?
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Probably resembled modern Choanoflagellates (that lived 1.2 BYA to 800 MYA)
cause Choanoflagellates resemble a type of cell found in basal animals (like sponges) |
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Basal
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Found at the base of the evolutionary tree
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Choanocytes
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In sponges, the colonial protists that trap food particles and feed the sponge, evidence of choanoflagellates as a common ancestor to animals
Generate water current into the sponge and trap and ingest food particles |
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Porifera
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phylum of sponges
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Metazoa
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35 phyla within, base of evolutionary tree for animals, cellular grade complexity, no gut, e.g. sponges
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“cellular grade” of complexity
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different cells in individuals perform different functions, but cells don't work together
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Eumetazoa
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second branch up the tree after Metazoa, tissue level complexity, have guts
All animals aside from sponges belong to this clade. •tissues: “tissue grade” of complexity •diploblastic or triploblastic •radially or bilaterally symmetric |
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Tissues grade complexity
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groups of similar cells working together perform a specific function
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Cell types in sponges
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Most basal metazoans, choanocytes, porocytes, epidermis, mesohyl, amoebocytes,
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Porocytes
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Water enters the sponge through porocyte cells that span the body wall
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Epidermis
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The body is covered by tightly-packed epidermal cells
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Mesohyl
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The body consists of two layers of cells, separated by a gelatinous layer….the mesohyl
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Amoebocytes
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Amoebocytes are found throughout the mesohyl take up food from the water & from choanocytes, digest it and carry it to other cells manufacture tough skeletal fibers within the mesohyl
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Spicules
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Tough skeletal fibers within the mesohyl which provide support in some sponge species. They are
made from calcium carbonate or silica. |
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Spongin
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In other sponge species, support is provided by flexible fibers of a collagen protein
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Suspension feeders
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Water exits the spongocoel through the osculum, there is a constant flow of water into and out of the sponge and they feed on suspended particles in the water
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Reproduction in sponges (phylum Porifera)
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Most are hermaphrodites
individuals produce both sperm AND eggs and almost all are sequentially hermaphroditic first one sex, then the other. Saltwater sponges: Gametes are produced by the choanocytes and/or amoebocytes. Sperm released into water, eggs remain in mesohyl. Eggs are fertilized in mesohyl. Flagellated larvae disperse from parent and settle on substrate to make new sponges. Freshwater sponges: Sponges can also reproduce asexually by producing specialized cells called gemmules. |
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Gemmules
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Cells produced by asexually reproducing sponges. Released into the water and drift around until they release amoeboctyes that differentiate into a newly
developing sponge |
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Radially symmetric Eumetazoans
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Paraphylatic- the Cnidarians & the Ctenphorans
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Cnidarians' body plans
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Corals, jellies, anemones, hydras
Two body plans: •sessile polyp (cylindrical forms that adhere to the substrate) •mobile medusa (flattened free swimming form with mouth facing down) Some alternation of generation include both forms. Others don't. Corals and sea anemones do not have medusae. Open-ocean jellyfish tend to skip the polyp stage |
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Characteristics of Cnidarians
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•have radial symmetry
•and are diploblastic (only have ectoderm & endoderm) •they also have a single opening that serves as a mouth and an anus! •and they have stinging cells!!! (called cnidocytes) |
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Cnidocytes
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Stinging cells in Cnidarians
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Class Hydrozoa
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Portuguese Man O War, Hydras, Obelias, some Corals- Most marine, a few fresh water, both polyp and medusa stages in most species, polyp stage in colonial species
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Class Scyphozoa
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Jellies- All marine, polyp stage reduced, free swimming medusas up to 2m in diameter
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Cubozoa
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Box jellies, sea wasps- all marine, box shaped, some TOXIC
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Anthozoa
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Sea anemones, most coral, sea fans- all marine, medusa stage completely absent, sessile, many colonial
Most corals have a symbiotic relationship with photosynthetic protists |
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Ctenophorans
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"comb jellies"
•~ 100 species •COLLOBLASTS: adhesive patches on tentacles for catching prey •Eight rows of comb-like plates for swimming •Complete gut—mouth and anus |
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Colloblasts
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Adhesive patches on tentacles for catching prey
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