Biol120 – Lecture 4: What Are Animals?

30 vocabulary flashcards covering key terms in animal characteristics, development, body plans, and embryology from Lecture 4.

Kingdom Animalia

The taxonomic kingdom comprising multicellular, heterotrophic, motile organisms with differentiated tissues and organs.

Multicellular

Made up of many cells that work together within one organism.

Heterotrophic

Obtaining organic nutrients by consuming other organisms rather than producing food autotrophically.

Locomotion

The ability of an organism to move from place to place for food, reproduction, or other needs.

Cellular Level of Organisation

Body organisation where cells function largely independently; characteristic of sponges (Porifera).

Tissue Level of Organisation

Body plan in which similar cells work together as tissues, seen in diploblastic and some triploblastic animals.

Organ Level of Organisation

Different tissue types combine to form organs that perform specific functions, typical of bilaterally symmetrical triploblastic animals.

Diploblastic

Having two primary germ layers (ectoderm and endoderm) in the embryo; e.g., Cnidaria and Ctenophora.

Triploblastic

Having three primary germ layers (ectoderm, mesoderm, endoderm) in the embryo; typical of most animal phyla.

Nematode

Roundworm; the most numerically abundant group of animals on Earth, especially in soil habitats.

Gamete

A haploid reproductive cell produced by meiosis—egg in females, sperm in males.

Zygote

The diploid cell formed by the fusion of an egg and a sperm at fertilisation.

Cleavage

The series of rapid mitotic divisions of a zygote that increase cell number while reducing individual cell size.

Blastula

A hollow ball of cells produced after cleavage; surrounds the blastocoel cavity.

Blastocoel

The fluid-filled cavity inside the blastula.

Gastrulation

Developmental process in which the blastula folds inward to form the gastrula and establish embryonic germ layers.

Gastrula

Embryonic stage following gastrulation that possesses either two (diploblastic) or three (triploblastic) germ layers.

Archenteron

The primitive gut cavity formed during gastrulation.

Blastopore

The opening of the archenteron to the exterior; becomes the mouth in protostomes and the anus in deuterostomes.

Ectoderm

The outer embryonic germ layer that gives rise to epidermis and nervous tissue.

Mesoderm

The middle germ layer that forms muscles, blood, reproductive organs, and connective tissues including bone.

Endoderm

The inner germ layer that develops into the digestive tract lining and associated organs.

Protostome

A clade of animals (e.g., molluscs, annelids, arthropods) where the blastopore becomes the mouth, cleavage is spiral and determinate, and the coelom forms by splitting.

Deuterostome

A clade of animals (e.g., echinoderms, chordates) where the blastopore becomes the anus, cleavage is radial and indeterminate, and the coelom forms from paired mesodermal pouches.

Coelom

A fluid-filled body cavity completely lined by mesoderm and distinct from the gut.

Asymmetry

Body form lacking any plane that produces mirror images; characteristic of sponges.

Radial Symmetry

Body plan in which any longitudinal slice through the central axis yields mirror images; seen in cnidarians.

Bilateral Symmetry

Body design with only one plane (sagittal) producing mirror images, featuring distinct anterior/posterior ends and cephalisation.

Pentaradial Symmetry

Five-part radial symmetry found exclusively in adult echinoderms, derived from a bilaterally symmetrical larva.

Cephalisation

Evolutionary development of a head region with sensory and neural organs concentrated at the anterior end.