Final Flashcards
has two embryonic cell layers; ectoderm and endoderm
diploblast
has three embryonic cell layers; ectoderm, mesoderm, and endoderm
triploblast
each of the three layers of the cells that are formed in the early embryo
germ layer
outermost layer of cell
ectoderm
innermost layer of cell
endoderm
middle layer
mesoderm
a structure containing a number of nerve cell bodies
ganglia
living and non-living things when rotated through a center of rotation by more than 0° and less than 360°, exactly match each other in orientation and shape.
radial symmetry
symmetrical halves on either side of a unique plane
bilateral symmetry
The formation in animals of a distinct anterior region (the head) where sense organs and a mouth are clustered
cephalization
an internal, usually fluid-filled body cavity that is completely or partially lined with mesoderm
coelom
A bilaterian animal that lacks an internal body cavity (coelom)
acoelomate
an animal that has a true coelom, completely lined with mesoderm
coelomate
A system of body support involving a body wall in tension surrounding a fluid or soft tissue under compression
hydrostatic skeleton
A member of a major lineage of animals that are bilaterally symmetrical at some point in their life cycle, have three embryonic germ layers, and have a coelom (or evolved from ancestors that had a coelom). Includes all protostomes and deuterostomes
Bilateria
A major lineage of bilaterian animals including arthropods, mollusks, and annelids; sister group to deuterostomes
protostome
A major lineage of bilaterian animals that includes echinoderms and chordates; named for the embryonic development of the anus before the mouth; sister group to protostomes
deuterostome
The process of coordinated cell-shaped changes and movements, including the movement of some cells from the outer surface of the embryo to the interior that results in the formation of the three germ layers and establishes the axes of the embryo
gastrulation
A major lineage of protostomes that grow by shedding their external skeletons (molting) and expanding their bodies; includes arthropods, nematodes, and other groups
Ecdysozoa
A major lineage of protostomes that grow by extending their skeletons rather than by molting; many phyla have a specialized feeding structure (lophophore) and/or ciliated larvae (trochophore); includes rotifers, flatworms, segmented worms, and mollusks
Lophotrochozoa
Division of the body or a part of it into a series of similar structures; exemplified by the body segments of insects, annelid worms, and vertebrates
segmentation
One of the three major chordate lineages, comprising animals with a dorsal column of cartilaginous or bony structures (vertebrae) and a skull enclosing the brain; includes fishes, amphibians, mammals, and reptiles (including birds)
vertebrates
A non-monophyletic group composed of animals without a backbone; includes about 95 percent of all animal species
invertebrates
a rasping feeding appendage in mollusks such as gastropods
radula