Introduction to Animal Diversity and Lophotrochozoans

Animals

Multicellular eukaryotes that ingest food.

Heterotrophs

Organisms that consume organic substances for energy.

Body Symmetry

Arrangement of body parts around an axis.

Germ Layers

Embryonic layers forming different tissues.

Ectoderm

Outer germ layer forming skin and nervous system.

Mesoderm

Middle germ layer forming muscles and organs.

Endoderm

Inner germ layer forming gut lining and organs.

Gametes

Reproductive cells produced through meiosis.

Fertilization

Union of egg and sperm to form zygote.

Internal Fertilization

Sperm and egg unite inside a parent's body.

External Fertilization

Gametes released into the environment for fertilization.

Porifera

Phylum of sponges lacking true tissues and organs.

Ostium

Pores through which water enters a sponge.

Osculum

Opening through which water exits a sponge.

Choanocytes

Flagellated cells creating water currents in sponges.

Cnidaria

Phylum including corals, jellyfish, and sea anemones.

Radial Symmetry

Body plan arranged around a central axis.

Diploblastic

Organisms with two tissue layers: ectoderm and endoderm.

Cnidocytes

Stinging cells used by cnidarians to capture prey.

Protostomes

Animals with protostome embryonic development.

Cephalization

Development of a head region with sensory organs.

Triploblastic

Organisms with three germ layers: ectoderm, mesoderm, endoderm.

Platyhelminthes

Phylum of flatworms, lacking a true body cavity.

Acoelomate

Organisms without a body cavity, like flatworms.

Proglottids

Reproductive segments of tapeworms.

Annelida

Phylum of segmented worms with a true coelom.

Metameric

Body divided into repeating segments.

Mollusca

Phylum including snails, clams, and octopuses.

Radula

Tongue-like structure with teeth in mollusks.

Eucoelomate

Organisms with a true coelom.