Molluscs, Arthropods, Lophophorates, Echinoderms, and Invertebrate Chordates

Molluscs, Arthropods, Lophophorates,

Echinoderms, and Invertebrate Chordates

MolluscsName 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 calciumHosts to parasitesCan 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

CheliceratesHorseshoe crabsSea 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)

SessileBody Structure:

Lack distinct headFeeding:

Possess lophophoreFeeding deviceAlso 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)SessileBody structure:

Covered by a tunic composed of polysaccharides

Reproduction:Asexual: in

coloniesSexual:

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