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36 Cards in this Set

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Metamorphosis

when an organism changes from a juvenile to an adult form

Metazoa

collective term/group of all animals

Parazoa

animals that do not posses specialized tissue types or organs; single phylum (Porifera)

Eumetazoa

animals that have one or more types of tissue and, for the most part, different types of organs

Radiata

symmetric animals that can be divided equally by any longitudinal plane passing through the central axis; often circular or tubular in shape

Bilateria

symmetric animals that be divided along a vertical plane at the midline to create two halves

Dorsal

upper sideof animal body plan

Ventral

lower side of animal body plan

Anterior

side of animal body plan where the head is found

Posterior

tail end of animal body plan

Cephalization

the localization of sensory structures at the anterior end of the body

Germ layers

Embryonic layer

Gastrulation

process in which the growing embryo of animals develops different layers of cells

Cleavage

a succession of rapid cell divisions with no significant growth that produces a blastula

Blastula

a hollow sphere of cells

Gastrula

a structure created through gastrulation where an area of the blastula folds inward

Endoderm

the innermost layer of cells formed during gastrulation; lines the primitive digestive tract

Ectoderm

the outermost layer of cells formed during gastrulation that covers the surface of the embryo and differentiates into the epidermis and nervous system

Mesoderm

a layer of cells formed during gastrulation that develops between the ectoderm and endoderm; gives rise to the skeleton, muscles, and much of the circulatory system; only found in Bilateria

Triploblastic

animals having three distinct germ layers; bilateral animals

Diploblastic

animals that only have an endoderm and ectoderm; radial animals

Blastopore

the opening of the primitive digestive tract (archenteron) to the outside

Protostomes

animals where the blastopore becomes the mouth and, if present, the anus form from a secondary opening

Deuterostomes

animals where the blastopore becomes the anus and the mouth is formed from the secondary opening

Determinate cleavage

when the fate of each embryonic cell is determined very early on; if one of the cells is removed from a four-cell protostome embryo, neither the single cell nor the remaining three-cell mass can form viable embryos and development stops

Indeterminate cleavage

each cell produced retains the ability to develop into a complete embryo; deuterostome development; in humans if individual embryonic cells separate from one another early in development, twins can result

Coelom

fluid-filled body cavity

Coelomates

animals with a (true) coelem completely lined with a mesoderm

Pseudocoelomates

animals with a fluid-filled cavity that isn't completely lined by tissue derived from a mesoderm

Acoelomates

animals that lack a fluid-filled body cavity

Hydrostatic skeleton

a fluid-filled body cavity surrounded by muscles that gives support and shape to the body of organisms; muscle contractions at one part of the body pushes this fluid toward another part of the body; observed in earthworms

Hox genes

involved in determining the spatial patterning of the body and appendages; present in all animals

Ecdysozoa

a clade of animals that secrete a nonliving cuticle that they molt when it becomes too small before secreting a new, larger one; consists of nematodes and arthropods

Lophotrochozoa

a major protostome clade encompassing mollusks, annelids, and many other phyla

Lophophore

a horseshoe-shaped crown of tentacles used for feeding; found in rotifers, bryozoans, and brachiopods

Trochophore larva

a distinct larva stage characterized by a band of cilia around its middle that is used for swimming