Biology 230 - Animal Diversity Part 1

characteristics of animal

multicellularity, heterotrophy, and specialized tissues.

where did animals evolve from

evolved from colonial protists in aquatic environment, Because protists

are both heterotrophic and eukaryotic, scientists have inferred that

multicellular invertebrates may have developed from colonies of

loosely connected, flagellated protists,

Acoelomates

An animal without a body cavity.

Amoebocytes

Cells found in sponges that crawl about within the body wall and deliver the nutrients to

the rest of the organism.

Bilateral symmetry

two equal halves of a body mirror each other

Blastocoel

The central cavity of the blastula.

Blastopore

an opening that develops in the blastula

Blastula

the stage of an embryo before gastrulation

Cephalization

the concentration of nerve tissue and sensory organs at the anterior end of an organism

Choanocyte

Sponge cell that creates a current by beating its flagella, traps food particles and digests

them.

Cnidocyte

Specialized cell in cnidarians used for defense and capturing prey.

Coelom

a body cavity that is completely lined by mesoderm and that contains the internal organs of

an animal

Cuticle

a waxy or fatty and watertight layer on the external wall of epidermal cells

Deuterostomes

an organism whose embryonic blastopore develops into an anus, whereas its mouth devel-

ops from a second opening at the opposite end of the archenteron; usually characterized by

an embryo that undergoes parallel cleavage and the coelom develops from outpockets of the

gut.

Differentiation

the structural and functional specialization of cells during an organism’s development

Ectoderm

the outermost of embryo that develops into the epidermis and epidermal tissues, the nervous system, external sense organs, and the mucous membranes lining the mouth and anus

Endoderm

the innermost germ layer of the animal embryo; develops into the epithelium of the phar-

ynx, respiratory tract, digestive tract, bladder, and urethra

Gastrodermis

Inner cell layer that lines the gastrovascular cavity.

Gastrovascular cavity

Space inside cnidarians where food is digested and absorbed.

Gastrula

the embryo in the stage of development after the blastula; contains the embryonic germ lay-

ers

Gastrulation

the transformation of the blastula into the gastrula or the formation of the embryonic germ

layers

Gemmule

sponges, dormant, food-filled ball of amoebocytes surrounded by protective coat of organic material and spicules.

Mesoderm

in an embryo, the middle layer of cells that gives rise to muscles, blood, and various systems

Mesoglea

Middle jelly-like layer found in cnidarians.

Nematocyst

An organelle found inside the cnidocytes of cnidarians that pierces and poisons prey.

Planula

Ciliated larval form of jellyfish.

Primary host

the host from which the adult parasite gets its nourishment and in which sexual reproduc-

tion occurs

Proglottid

one of the many body sections of a tapeworm; contains reproductive organs

Protostomes

embryonic blastopore develops into mouth, coelom arises from within mesoderm, embryo has spiral cleavage

Pseudocoelom

body cavity not completely lined by mesoderm.

Radial symmetry

organized in a circle around a central

axis

Roundworms

smooth skin and a long, cylindrical, and unsegmented body with tapered ends

Scolex

the head of a tapeworm, which has hooks and suckers to adhere to the host tissues

Segmentation

the division of the body of an organism into a series of similar parts

Specialization

the evolutionary adaptation of a cell, organ, organism, or population for a particular func-

tion or environment

Spicules

needles of silica or calcium carbonate in the skeleton of some sponges

Spongin

a fibrous protein that contains sulfur and composes the fibers of the skeleton of some

sponges

Zooxanthallae

Algae that live symbiotically inside coral polyps. The algae provide nutrition for the coral

polyp while the polyp serves as habitat and provides nutrients to the algae.

archenteron

the primitive gastric cavity of an embryo

cleavage

The series of cell divisions that occurs immediately following fertil-

ization is termed cleavage During cleavage, mitotic divisions rapidly increase the number

of cells, but the cells do not grow in size. Thus, cleavage yields

smaller and smaller individual cells. Cleavage increases the surface

area–to-volume ratio of each cell, which enhances gas exchange and other environmental interactions.

radial cleavage

deuterostomes have it, cell divisions parallel to or at right angles to the axis from one pole of the blastula to the other.

spiral cleavage

protostomes, cells divide in spiral arrangement. In embryos of echinoderms and chordates, blastopore develops into anus, second opening at other end of archenteron becomes mouth.

appendage

a structure that extends from the main body, such as a limb, tentacle, fin, or wing

elephantiasis

a disease in humans that is caused by filarial worms and that is characterized by fluid accumulation that results in thickened skin around swollen extremities

pseudocoelomate

a body cavity not completely lined by mesoderm

filarial worm

cause diseases such as elephantiasis in humans and heartworm disease in dogs and cats

pinworm

a nematode worm parasite that lives in the intestine of humans and animals; females lay their eggs around the anus, which causes itching

flame cell

in a flatworm, a cell that has flagella or cilia that move waste products through the body

ganglia

a cluster of nerve cells

intermediate host

the host from which the larvae derive their nourishment

pharynx

in flatworms, the muscular tube that leads from the mouth to the gastrovascular cavity

schistosomiasis

caused by parasitic blood fluke genus Schistosoma affects the skin, intestines, liver, vascular system

tegument

external surface of fluke, protects against enzymes secreted by digestive tract.

nerve net

system of nerve cells in cnidarians

medusa

bell shaped free swimming form of cnidarians

polyp

vase shaped sessile form of cnidarian

medusa

bell shaped free swimming form of cnidarians

tentacle

a flexible appendage with which an animal feeds itself, grasps objects, or feels its environment