Molluscs, Arthropods, Lophophorates, Echinoderms, and Invertebrate Chordates

Molluscs Name means “soft- bodied” Usually covered by shell made of calcium carbonate Ex: chitons, snails (gastropods), clams (bivalves), octopods, squid, Range in size from microscopic to giant

Body Structure: Head-foot region Covered by mantle Used for locomotion Can help form shell Visceral mass Radula  contains teeth Adapted for scraping, piercing, tearing, or cutting pieces of food

Reproduction and development: Mainly sexual Can have separate sexes or be hermaphrodites Type of feeding: Herbivores, Carnivores, Filter feeders, Suspension feeders, Scavengers, Deposit feeders

Ecological roles: Source of food and calcium Hosts to parasites Can cause commercial damage

Arthropods Name means “jointed-leg” Body Structure: Paired jointed appendages for locomotion, mouthparts, sensory structures Hard exterior (exoskeleton) Made of protein and chitin Sophisticated sense organs  highly developed nervous system Segmented body

Reproduction: Herbivores, Carnivores, Filter feeders, Suspension feeders, Scavengers, Deposit feeders Chelicerates Horseshoe crabs Sea siders

Mandibulates Decapods: crabs, lobsters, true shrimp Mantis shrimp Krill Amphipods Copepods Barnacles Ecological roles: Food source Common symbionts Nutrient recycling Can cause commercial damage

Lophophorates (Phoronida) Sessile Body Structure: Lack distinct head Feeding: Possess lophophore Feeding device Also used for gas exchange Ciliated tentacles around mouth

Reproduction: Asexual by budding or fission Some are hermaphrodites Some have separate sexes Phoronids  wormlike Secrete a leathery tube around the body Bryozoans Brachiopods  lamp shells Ecological roles Filter feeders Supply food Fouling ship’s bottoms

Echinoderms Name means “spiny skin” Mostly benthic Ex: sea stars, sea urchins, sea cucumbers Body Structure: Radial symmetry Endoskeleton of calcium carbonate (ossicles) Water vascular system Used for locomotion, feeding, and circulating internal fluids

Reproduction Asexual and sexual Feeding Herbivores, carnivores, filter feeders, deposit feeders, scavengers Ophiuroids Brittle stars, basket stars, serpent stars Crinoids Sea lilies, feather stars Ecological roles Source of food for molluscs, sea otters, spider crabs, and humans Predators Destroy kelp forests

Tunicates (Urochordates) Sessile Body structure: Covered by a tunic composed of polysaccharides Reproduction: Asexual: in colonies Sexual: hermaphrodites

Feeding: Filter feeders on plankton Ecological roles: Channels nutrients for other organisms Can have symbiotic relationship with photosynthetic bacteria Widely distributed in all seas Ex: sea squirts, salps, larvaceans

Cephalochordates Fish-like chordates (lancelets) Lack bones Body resembles an eel Reproduction: Separate sexes External fertilization Feeding: Feed on organic material from particles filtered from the water Ecological role: Channels nutrients for other organisms

Arrowworms (Chaetognatha) In marine plankton (tropical water) Body Structure: Body is torpedo-shaped Grasping spines around the mouth Reproduction: Hermaphrodites Feeding: Predators that feed on zooplankton Carnivores Ecological role: Channels nutrients for other organisms