Chapter 32 - An Overview of Animal Diversity Flashcards
Animals -
Multicellular eukaryotes
Tissues -
groups of similar cells that act as a functional unit
Cleavage -
a succession of mitotic cell divisions without cell growth between the divisions
A blastula -
a multicellular embryonic stage
Process of gastrulation -
during which the layers of embryonic tissues that will develop into adult body parts are produced
A gastrula -
resulting developmental stage of gastrulation
A larva -
a sexually immature form of an animal that is morphologically distinct from the adult, usually eats different food, and may even have a different habitat than the adult
Metamorphosis -
a developmental transformation that turns the animal into a juvenile that resembles an adult but is not yet sexually mature
Hox genes -
play important roles in the development of animal embryos, controlling the expression of many other genes that influence morphology
Ediacaran biota
members of an early group of mostly soft-bodied multicellular eukaryotes, the first generally accepted macroscopic fossils of animals from about 560 million years ago
Cambrian explosion
wave of animal diversification occuring 535–525 million years ago, early in the Cambrian period of the Paleozoic era
bilaterians
a clade whose members typically have a two-sided or a bilaterally symmetric form and a complete digestive tract, an efficient digestive system that has a mouth at one end and an anus at the other.
A body plan -
is a particular set of morphological and developmental traits that are integrated into a functional whole—the living animal
Sessile -
living attached to a substrate
planktonic
drifting or weakly swimming, such as jellies, commonly called jellyfishes
Ectoderm
the germ layer covering the surface of the embryo
Endoderm
the innermost germ layer, lines the pouch that forms during gastrulation (the archenteron) and gives rise to the lining of the digestive tract (or cavity) and to the lining of organs such as the liver and lungs of vertebrates
Diploblastic -
animal groups that have only these two germ layers
Mesoderm -
All bilaterally symmetrical animals have a third germ layer which fills much of the space between the ectoderm and endoderm
Triploblastic -
animals with bilateral symmetry and three germ layers
a body cavity -
a fluid- or air-filled space located between the digestive tract (endoderm) and the outer body wall (ectoderm)
a coelom -
a body cavity that forms from tissue derived from mesoderm. The inner and outer layers of mesoderm that surround the cavity connect and form structures that suspend the internal organs
a hemocoel -
a body cavity that forms between the mesoderm and endoderm. A hemocoel contains hemolymph, a fluid that functions in the internal transport of nutrients and waste
Spiral cleavage -
in which the planes of cell division are diagonal to the vertical axis of the embryo; as seen in the eight-cell stage of the embryo, smaller cells are centered over the grooves between larger, underlying cells
Determinate cleavage -
of some animals with protostome development rigidly casts (“determines”) the developmental fate of each embryonic cell very early
Radial cleavage -
the cleavage planes are either parallel or perpendicular to the vertical axis of the embryo; as seen at the eight-cell stage, the tiers of cells are aligned, one directly above the other
Indeterminate cleavage -
meaning that each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo
the archenteron
formed during gastrulation, an embryo’s developing digestive tube initially forms as a blind pouch which becomes the gut
Blastopore -
the indentation that during gastrulation leads to the formation of the archenteron
