Chapter 9: Molluscs, Arthropods, Lophophorates, Echinoderms, and Invertebrate Chordates

Molluscs, Arthropods, Lophophorates, Echinoderms, and Invertebrate ChordatesMolluscsName means soft-bodiedUsually covered by shell made of calcium carbonateEx: chitons, snails (gastropods), clams (bivalves), octopods, squid, Range in size from microscopic to giant

Body Structure:Head-foot regionCovered by mantleUsed for locomotionCan help form shellVisceral massRadula contains teethAdapted for scraping, piercing, tearing, or cutting pieces of food

Reproduction and development:Mainly sexualCan have separate sexes or be hermaphroditesType of feeding:Herbivores, Carnivores, Filter feeders, Suspension feeders, Scavengers, Deposit feeders

Ecological roles:Source of food and calciumHosts to parasitesCan cause commercial damage

ArthropodsName means jointed-legBody Structure:Paired jointed appendages for locomotion, mouthparts, sensory structuresHard exterior (exoskeleton) Made of protein and chitinSophisticated sense organs highly developed nervous systemSegmented body

Reproduction:Herbivores, Carnivores, Filter feeders, Suspension feeders, Scavengers, Deposit feedersCheliceratesHorseshoe crabsSea siders

MandibulatesDecapods: crabs, lobsters, true shrimpMantis shrimpKrillAmphipodsCopepodsBarnaclesEcological roles:Food sourceCommon symbiontsNutrient recyclingCan cause commercial damage

Lophophorates (Phoronida)SessileBody Structure:Lack distinct headFeeding:Possess lophophoreFeeding deviceAlso used for gas exchangeCiliated tentacles around mouth

Reproduction:Asexual by budding or fissionSome are hermaphroditesSome have separate sexesPhoronids wormlikeSecrete a leathery tube around the bodyBryozoansBrachiopods lamp shellsEcological rolesFilter feedersSupply foodFouling ships bottoms

EchinodermsName means spiny skinMostly benthicEx: sea stars, sea urchins, sea cucumbersBody Structure:Radial symmetryEndoskeleton of calcium carbonate (ossicles)Water vascular systemUsed for locomotion, feeding, and circulating internal fluids

ReproductionAsexual and sexualFeedingHerbivores, carnivores, filter feeders, deposit feeders, scavengersOphiuroidsBrittle stars, basket stars, serpent starsCrinoidsSea lilies, feather starsEcological rolesSource of food for molluscs, sea otters, spider crabs, and humansPredatorsDestroy kelp forests

Tunicates (Urochordates)SessileBody structure:Covered by a tunic composed of polysaccharidesReproduction:Asexual: in coloniesSexual: hermaphrodites

Feeding:Filter feeders on planktonEcological roles:Channels nutrients for other organismsCan have symbiotic relationship with photosynthetic bacteriaWidely distributed in all seasEx: sea squirts, salps, larvaceans

CephalochordatesFish-like chordates (lancelets)Lack bonesBody resembles an eelReproduction:Separate sexesExternal fertilizationFeeding:Feed on organic material from particles filtered from the waterEcological role:Channels nutrients for other organisms

Arrowworms (Chaetognatha)In marine plankton (tropical water)Body Structure:Body is torpedo-shapedGrasping spines around the mouthReproduction:HermaphroditesFeeding:Predators that feed on zooplanktonCarnivores Ecological role:Channels nutrients for other organisms