Lab 7B: Key Characters to Animal Diversity

What are three types of characters that are used to identify clades of animals?

body symmetry, pattern of development in the embryonic stages, and specific embryonic characters in early development.

What are the stages of embryonic development?

Fertilization, cleavage, gastrulation, organogenesis

What are three types of body symmetry?

asymmetry, radial symmetry, bilateral symmetry

asymmetry

having no symmetry

radial symmetry

symmetry around a central axis

bilateral symmetry

symmetry with right-left mirror images

cephalization

formation of a head

anterior

head end of an animal

posterior

away from the head end, or rear end of an animal

dorsal

top or back side

ventral

front or belly side

embryology

study of the embryo, of the growth and differentiation that occurs during early development

What is the difference between growth and differentiation?

In growth, cells or organs become larger. In differentiation, cells change from one type into another (they become specialized into different tissues and organs)

fertilization

Stage of embryonic development; the union of sperm and egg into a zygote

totipotent

a cell like a zygote that can differentiate into any type of cell

pluripotent

a cell like a stem cell that can differentiate into any of the three germ layers (not no longer any cell such as the placenta)

unipotent

a cell that can only grow into one kind of cell or tissue usually because it is already highly differentiated

cleavage

Stage of embryonic development; specialized division of cells after fertilization (blastomeres) into a hollow ball of cells (blastula)

blastomere

During cleavage: the early undifferentiated cells

morula

During cleavage: the solid ball of cells

blastula

During cleavage: the hollow ball of cells

blastocoel

During cleavage: the fluid-filled cavity within the blastula

What are some of the patterns of cleavage that identify evolutionary clades of animals?

The size of cells (blastomeres) and their location in the embryo; the kind of blastomeres (determinate and indeterminant)

gastrulation

Stage of embryonic development; reorganization of the hollow ball of cells (blastula) into germ layers

germ layers

cell layers of the embryo- the ectoderm, mesoderm and endoderm

ectoderm

outermost germ layer (develop into skin and nervous system)

mesoderm

middle layer (develop into circulatory and reproductive systems, muscles, and bones

endoderm

innermost germ layer (develops into lining of digestive and respiratory tracts, as well as liver, pancreas and other glands

blastopore

During gastrulation: the pore or opening formed in the hollow blastula

archenteron

during gastrulation: the deeper cavity formed following the formation of the blastopore. This first body cavity becomes the gut.

protostome

Organisms in which the blastopore becomes the mouth. "mouth first"

deuterostome

Organisms in which the blastopore becomes the anus. "mouth second"

diploblastic

animals having two cell layers (no mesoderm)

triploblastic

animals having three cell layers (endoderm, mesoderm and ectoderm)

coelom

A second body cavity that forms between the germ layers. Organs are suspended and protected in this cavity.

acoelomate

not having a coelom or enclosed body cavity

pseudocoelomate

having a fluid filled space, but it is not a true cavity formed from the mesoderm

coelomate

a true body cavity formed from the mesoderm

What kinds of characters during gastrulation are used to identify evolutionary clades of animals?

Fate of the blastopore or first opening (becomes the mouth or the anus), the number of germ layers (diploblastic or triploblastic), and presence and kind of coelom or second body cavity (acoelomate, pseudocoelomate, and coelomate)

organogenesis

Stage of embryonic development; process of cells in germ layers becoming body organs.

neurulation

stage of organogenesis; formation of brain and spinal cord in vertebrates

notochord

early neurulation; the rod-like structure that forms from the mesoderm

neural tube

early neurulation; this becomes the brain and spinal cord and forms from the ectoderm

What are kinds of characters during organogenesis that are used to identify evolutionary clades of animals?

All the different kinds and forms of organs. The kinds of brains and spinal cords formed during neurulation are critical to identifying vertebrate animals.