Introduction to Animal Diversity: Invertebrates (8C)

Bilateria

Animals with bilateral symmetry in body plan.

Protostomia

Animals where mouth develops before anus.

Lophotrochozoa

Group with lophophore and trochophore larval stages.

Lophophore

Ciliated feeding structure in certain invertebrates.

Trochophore

Free-swimming larval stage in some invertebrates.

Phylum Platyhelminthes

Includes flatworms, both free-living and parasitic.

Phylum Rotifera

Microscopic animals with a ciliated crown.

Phoronida

Horseshoe worms with lophophore feeding structure (lophophore coiled around mouth).

Bryozoa

Colonial animals that secrete and live in zoecium for protection. composed of chitin and calcium carbonate.

Brachiopoda

Marine animals with two shells, have a similar appearance to clams. Dorsal and ventral shells are from top to bottom side. attach to substrate with a muscular pedicle.

Phylum Mollusca

Diverse group including snails, clams, and octopuses. fleshy bodies enclosed in a hard shell. mostly separate sexes, even though some are hermaphroditic

Bivalvia

Class of mollusks with two hinged shells.

Polyplacophora

Class of mollusks known as chitons.

Gastropoda

Class of mollusks including snails and slugs.

Cephalopoda

Are marine predators and invertebrates. Class of mollusks including squids and octopuses.

Radula

Tongue-like organ in mollusks for feeding.

Phylum Annelida

Segmented worms including earthworms and leeches.

Phylum Nematoda

Roundworms, often microscopic, many are parasitic.

Pseudocoelomate

Organisms with a body cavity not fully lined.

Phylum Arthropoda

Largest animal phylum, joint-legged invertebrates. they have a hard exoskeleton, which results in them being common fossils.

Exoskeleton

Hard outer structure providing support and protection.

Functions of the exoskeleton

protection, support against gravity, helps prevent dehydration.

main arthropod subphyla

Subphylum Chelicerata, Subphylum Myriapoda, Subphylum Crustacea, and Subphylum Hexapoda.

Subphylum Chelicerata

Includes spiders and scorpions, with chelicerae.

Regions of the Subphylum Chelicerata

Cephalothorax (fusion of the head and thorax), and abdomen.

Subphylum Myriapoda

Includes centipedes and millipedes, many legs.

Subphylum Hexapoda

Insects with three pairs of legs and wings.

Subphylum Crustacea

Aquatic arthropods with two pairs of antennae, a hardened exoskeleton, and appendages that divide into three branches.

The body regions, segments, and appendages are

specialized for different functions.

Deuterostomia

Having a deuterostome pattern of development. Group including echinoderms and chordates, anus first.