Kingdom Animalia Biology 2 Study Guide

Collection of key terms and definitions related to the Kingdom Animalia for exam preparation.

Multicellularity

Body composed of many specialized cells that allows division of labor among cells.

Heterotrophs

Organisms that cannot photosynthesize and must ingest/absorb other organisms for energy.

Nervous tissue

Specialized cells that transmit electrochemical signals allowing sensation and coordinated response.

Muscle tissue

Cells that contract, unique to animals, powering locomotion and internal movements.

Hox gene clusters

Master regulatory genes controlling body axis patterning; mutations can lead to major changes in body plan.

Cambrian Explosion

A sudden diversification of animal phyla occurring around 533-525 million years ago.

Invertebrates

Animals without a backbone, making up approximately 96% of all animal species.

Bauplan

The basic body design or ground plan of each major taxonomic group.

Epithelia

Tissue types that cover body surfaces and line cavities in multicellular organisms.

Acoelomate

Organisms that have no body cavity; solid body structure.

Pseudocoelomate

Organisms that have a body cavity present but not fully lined by mesoderm.

Eucoelomate

Organisms with a true coelom that is fully lined by peritoneum from mesoderm.

Protostomes

Animals in which the blastopore becomes the mouth during embryonic development.

Deuterostomes

Animals in which the blastopore becomes the anus during embryonic development.

Chordates

Animals that possess a notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail, and endostyle.

Cnidocytes

Specialized cells in cnidarians containing cnidae for stinging prey.

Gastrovascular cavity

A digestive cavity with only one opening serving as both mouth and anus.

Amniotic egg

A type of egg that provides a self-contained environment for the developing embryo, allowing life on land.

Ectothermic

Organisms that rely on external environmental heat sources to regulate their body temperature.

Endothermic

Organisms that can generate and regulate their own body heat internally.

Mammary glands

Glands in female mammals that produce milk to nourish young.

Paedomorphosis

The retention of juvenile features in the adult form of an organism.

Echinoderms

Marine animals with a calcareous endoskeleton and pentamerous radial symmetry.

Lateral line system

A sensory system used by aquatic animals to detect water movements and vibrations.

Respiratory system in fish

Gills function for gas exchange, usually operating on counter-current exchange principles.

Osmoregulation in fishes

Methods by which fish regulate their internal salt and water concentration relative to their environment.

Crustaceans

Aquatic arthropods with a chitinous exoskeleton, jointed limbs, and two pairs of antennae.

Amphibians

Ectothermic tetrapods that typically require water for reproduction and have a dual life cycle.

Reptiles

Ectothermic vertebrates with tough, scaly skin, and internal fertilization.