• consists annelids, mollusks and arthropods
• development of the mouth from the balstospore
• spiral determinate cleavage

• consists of echinoderms and chordates
• development of the anus from the balstospore
• radial and inderminate cleavage

• the opening of the archenteron in the gastrula that develops into the mouth in protostomes and the anus in deuterostomes 

• the concentration of sensory equipment on the anterior end of the body, head develops faster than the rest of the body

• One notorious nematode is Trichinella spiralis , the worm that causes trichinosis. Humans acquire this nematode by eating undercooked infected pork or other meat with juvenile worms encysted in the muscle tissue. Within the human intestine, the juveniles develop into sexually mature adults. Females burrow into the intestinal muscles and produce more juveniles, which bore through the body or travel in lymph vessels to encyst in other organs, including skeletal muscles.

• any of a group of parasitic worms of the family Filariidae (phylum Nematoda) that usually require two hosts, an arthropod (the intermediate host) and a vertebrate (the primary host), to complete the life cycle. The larval phase occurs within the body of a biting insect. The mature (reproductive) phase occurs in the body of an animal bitten by the insect.

• tough skeletal fibers made from calcium carbonate or silica within the mesohyl; used to hold the sponge together 

• a fluid filled body cavity completely lined by tissues derived from the mesoderm; ex. annelids

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• a flagellated feeding cell found in sponges; also called a collar cell in which it traps food particles around the base of its flagella

Clitellum

• a special organ that secretes a mucous cocoon during the cross fertilization of earthworms
• this cocoon slides along the worm picking up the eggs and sperm then is slipped off the worm and placed in the soil

Cnidoblasts

• The floating, flattened, mouth-down version of the cnidarian body plan

• the sessile variant of the cnidarian body plan

• type of reproduction in which females produce offspring from unfertilized eggs

• asexual means of propogation in which outgrowths from the parent form and pinch off to live indepndently or else remain attached to eventually form extensive colonies

• symmetry in which an organism can be divided along any plane through a central axis (starfish, hydra)

• irregular shape, cant really be divided (sponges)

• can be divided longitudinally into left/right halves / form mirror images (flatworms, humans)

• organs of gas exchange in spiders, consisting of stacked plates contained in an internal chamber

• excretory structure in mollusks
• tubular structure that filters and cleans the coelom of nitrogenous wastes found in all coelomates (except arthropods and chordates)

• body cavity is not completely lined by tissue derived from the mesoderm (rotifers, roundworms)
• called pseudocoelomates (body cavity b/w endoderm and mesoderm

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• cross-walls that divide fungal hyphae into cells
• have pores large enough to allow ribosomes, mitochondria and even nuclei to flow from cell to cell (septum)

• bristles that provide traction for burrowing in earthworms

• during embryonic development an asymmetrical muscle forms and contraction of the muscle and uneven growth causes the visceral mass to rotate up to 180 degress so that the anus is placed on top of the head

• a shelled, water retaining egg that enables reptiles, birds, and egg-laying mammals to complete their life cycles on dry land

• refers to the type of development in which the young hatch from eggs that are retained in the mother's uterus (kangoroos) 

• development in which the young are born alive after having been nourished in the uterus by blood from the placenta

• development in which young hatch from eggs laid outside the mother's body

• a long flexible cord that runs along the dorsal axis of the body in the future postion of the vertebral column
• present in all chordate embryos
• provides skeletal support

• a sheet of muscle that forms the bottom wall of the thoracic cavity in mammals; active in ventilating the lungs

• tiny air tubes that branch throughout the insect body for gas exchange

• pores that can open or close to regulate air flow and limit water loss
• part of the tracheal system

• function in suspension feeding; filter food from water and then is flowed back out through the slits (chordates)

• develops from a plate of ectoderm that rolls into a tube located dorsal to the notochord; develops into the brain and spinal chord
• unique to chordates

• excretory organ of insects that empties into the digestive tract, removes nitrogenous wastes from the blood, and functions in osmoregulation

• the invaginated respiratory surfaces of terrestrial vertebartes, land snails, and spiders that connect to the atmosphere by narrow tubes

• a succession of mitotic division in which the zygote continuously divides to form a blastula

Blastula

• cleavage results in this multicellular formation stage
• a hollow ball of cells

• following the bastula is gastrulation (one end of the embryo folds inward, expands, and eventually fills the blastocoel, producing layers of tissue)
• result from the process is the gastrula containing the endoderm and ectoderm

• jawlike structures found in uniramians and crustaceans

• stinging components of the cnidocytes

• extensions of the body used to grab prey or other types of food

• clawlike feeding appendages characteristic of the chelicerate group

• a tapworm head
• armed with suckers and often menacing hooks that lock the worm to the intestinal lining of the host

• ciliated cells that waft fluid through branched ducts opening to the outside (an excretory structure to maintain osmoregulation)

• 3 main layers that form the various tissues of an animal body
• Ectoderm- gives rise to the outer covering of the animal and in some the central nervous system
• Endoderm- the innermost germ layer, lines the developing digestive tube, or archenteron, and gives rise to lining of d. tract and other organs
• Mesoderm- b/w the ecto and endo forms the muscle and most other organs b/w the digective tube and outer covering of the animal 

• Posterior to the scolex
• a long ribbon of units which are little more than sacs of sex organs

• animals without a cavity b/w the digestive tract and the outer body wall (Platyhelminthes, flatworms)

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• process in which an animal such as a reptile fish or amphibian must use enviornmental energy and behavioral adaptations to regulate its body temp.

• process in which animals such as birds or mammals mantain a constant body temp using metaoblic energy

• is the vertebrate analogue of the chitinized cuticle of insects and the waxy cuticle of land plants

• a vertebrate pocessing 2 pairs of limbs, such as amphibains, reptiles, birds, and mammals

• Paired blocks of mesoderm just lateral to the notochord of a vertebrate embryo

• a tube of cells running along the dorsal axis of the body, just dorsal to the notochord
• gives rise to the central nervous system

• a hard skeleton buried within the soft tissues of an animal, such as the spicules of sponges, the plates of echinoderms, and the bony skeleton of vertebrates

• a hard encasement on the surface of an animal, such as the shells of mollusks or the cuticles of arthropods, that provides protection and points of attachment for muscle

• an adaption, from a lung, that enables bony fishes to adjust their density and thereby control their buoyancy

• localized extentions of the body surface of many aquatic animals
• special for gas exchange