A Glossary of Terms from Lab 11:

acoelomate
A solid-bodied animal lacking a cavity between the gut and outer body wall.

amictic egg
A thin shelled diploid egg which cannot be fertilized. Instead, it develops by parthenogenesis. It is produced by rotifers when living conditions are optimal, and will develop to produce amictic females.

asexual reproduction
A type of reproduction involving only one parent that produces genetically identical offspring by budding or by the division of a single cell or the entire organism into two or more parts.

bilateral symmetry
An animal body structure in which the right and left halves of an organism are approximately mirror images of each other. Most higher invertebrates and all vertebrates have members which are bilaterally symmetrical.

blastema
An undifferentiated mass of animal cells that later forms a structure or organ either embryologically if through regeneration, for example the head of a flatworm.

caecum (pl. caeca)
A blind ending sac of the digestive system located between the large and small intestine.

cilium (plural, cilia)
A short cellular appendage specialized for locomotion.

contractile vacuole
An organelle that pumps excess water out of many freshwater protist cells.

dimorphism
An occurance of an organism in two forms. Sexual dimorphism refers to males and females. Dimorphism may occur in, for example, body form or colour.

dorsoventrally flattened
Flattened along the length of it's back ex. platyhelminths.

ectoderm
The outermost of the three primary germ layers in animal embryos; gives rise to the outer covering and, in some phyla, to the nervous system, inner ear, and lens of the eye.

endoderm
The innermost of the three primary germ layers in animal embryos; lines the archenteron and gives rise to the liver, pancreas, lungs, and the lining of the digestive tract.

enteron
The tubular passage that extends from mouth to anus.

epidermis
(1) the dermal tissue system in plants. (2) the outer covering of animals.

flame cell
A cell specialized for excretion found in platyhelminths.

hermaphrodite
Plants which possess both stamens and carpels in the same flower, while in animals it is organisms which possess both male and female sex organs

macronucleus
The larger of two nuclei found in some Protozoans and concerned with cell division. It appears to have mainly vegetative functions.

mesoderm
The middle primary germ layer of an early embryo that develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system.

micronucleus
The smaller of the two nuclei found in some Protozoans that is concerned with cell division.

mictic egg
A thin shelled haploid egg. If not fertilized, they will produce males by parthenogenesis. If fertilized, they will accumulate a large amount of yolk and secrete a heavier, resistant shell. These eggs are now dormant and can survive harsher environmental conditions until they develop into a diploid amictic female.

neoblast
Are undifferentiated cells arising from the parenchyma, which are rich in RNA. Thse cells form the blastema, which preceeds regeneration of planarians.

oral groove
A depression leading to the mouth in some invertebrates.

parasite
An organism that absorbs nutrients from the body fluids of living hosts.

parenchyma cells
A relatively unspecialized plant cell type that carries on most of the metabolism synthesizes and stores organic products, and develops into more differentiated cell types.

parthenogenesis
The development from an egg without fertilization by a sperm. The egg cell may be haploid or diploid.

phagocytosis
A type of endocytosis involving large, particulate substances.

pharynx
An area in the vertebrate throat where air and food passages cross; in flatworms, the muscular tube that protrudes from the ventral side of the worm and ends in the mouth.

polyp
The asexual reproducing, normally sedentary form of coelenterates such as the sea anemone.

proboscis
The elongated mouthparts of some insects.

proglottid
A reproductive division of a tapeworm.

Protozoan (plural, protozoa)
A protist that lives primarily by ingesting food, an animal-like mode of nutrition.

radial symmetry
Characterizing a body shaped like a pie or barrel, with many equal parts radiating outward like the spokes of a wheel; present in cnidarians and echinoderms.

scolex
The head of a tapeworm, found at the anterior end. It has hooks and suckers for attachment to it's host.

sexual reproduction
A type of reproduction in which two parents give rise to offspring that have unique combinations of genes inherited from the gametes of the two parents.