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Animals are _______ and are _____________.
How many animals are invertebrates?
In the animal kingdom, most are __________.
What are the simplest animals?
What do sponges attach to?
What do the bodies of most sponges lack? What are the cells not organized into?
- Tissues or organs
How is water drawn through the porocytes?
By the whipping action of the flagella
Where are the flagella found?
On special cells called chaonocytes lining the atrium
How does a sponge digest food?
Food particles sucked into the atrium are trapped in the collars and later ingested by the chaonocytes
What does the phylum Cnidaria include?
jellyfish, hydra, sea anenomes and corals
What symmetry do cnidarians and ctenophores have?
What are the stinging cells called on the tentacles?
Each cnidocyte has a small barbed harpoon called?
A nematocyst to spear prey
What are the two basic body forms of Cnidarians?
- Medusae: free-floating, gelatinous, often umbrella shaped, lots of mesoglea and tentacles and mouth face downward
- Polyps: cylindrical, pipe-shaped, attached, little mesoglea, and mouth and tentacles facing upward
What have most bilaterally symmetric animals evolved?
A definite head end (cephalization)
What are the simplest animals that have organs?
Flatworms don't have a ____________ so __________ and ___________ must pass through the solid body by __________.
circulatory system, oxygen, carbon dioxide, diffusion
What is the gut of a flat worm like? Benefit?
Highly branched, giving each cell access to food molecules
In flatworms, what is the only opening to the gut? What enters and exits it?
Mouth; food and waste
Other then flatworms, what do all other animals have?
An internal body cavity called a pseudocoelom
What were the improvements of the pseudocoelom?
- circulation: fludis within the body cavity can function as circulatroy system
- movement: fluid in body cavity makes animal's body rigid enabling muscle driven body movement
- organ function: body organs surrounded by body cavity can function without being distorted by surrounding muscles
What were nematodes/roundworms the first organsims to develop?
An internal body cavity
Where do most nematodes live?
in the soil
What three distinct regions is the body of a mollusk made up of?
- visceral mass: central sections containing body organs
- mantle: wrapped around visceral mass
- gills: filamentous projections, rich in blood vessels, capture oxygen from water and release carbon dioxide
What are the three classes of mollusks?
- Gastropods (snails and slugs): use muscular foot to crawl, mantle often secretes a hard protective shell
- Bivalves (clams, oysters, and scallops): secrete two-part shell (valve) with hinge; filter feeders
- Cephalopods (octopuses and squids): modified cavity that creates jet propulsion system to propel rapidly through water
What is a radula?
a rasping tongue-like organ
What mollusks don't have radula?
What is the advantage of segmentation?
Flexibility offered with segments having different functions
What three characteristics do all annelids share?
- repeated segments
- specialized segments
- connections between segments
What does each segment of an annelid have?
Digestive, excretory and locomotor organs
Fluids within coelom creates what?
A hydrostatic skeleton for rigidity
What were the first animals with jointed appendages?
What are the segments of adult arthropods?
What kind of skeleton do arthropods have?
Exoskeleton made of chitin
What is the arthropod skeleton limitation?
Can't support great amount of weight
What were the first animals to develop an endoskeleton?
What do echinoderms include?
- sea stars (starfish)
- sea urchins
- sand dollars
- brittle stars
- sea cucumbers
What kind of symmetry are echinoderms characterized by?
pentamorous radial symmetry
What special structures do echinoderms have?
Tube feet with suction pads situated at extremeties used for locomotion
What are tube feet controlled by?
hydraulically by water vascular system
What three things do all chordates have at some point in their lives?
- nerve cord: single, hollow dorsal nerve cord
- notochord: long, stiff rod that forms beneath nerve cord; between nerve chord and developing gut in early embryo
- pharyngeal slits: series of slits in wall of pharynx (located behind mouth, muscular tube connecting mouth to digestive tract and windpipe