I.Arthropoda B.Cirripedia (Barnacles) Active suspension feeders (filter feeders)Active suspension feeders (filter feeders) Use feathery cirri (modified swimming appendages)Use feathery cirri (modified swimming appendages) Sessile (attached to surfaces)Sessile (attached to surfaces) Fouling organisms (boats, whales)Fouling organisms (boats, whales) Resemble mollusks superficiallyResemble mollusks superficially Some parasitic formsSome parasitic forms Simultaneous hermaphroditesSimultaneous hermaphrodites Internal fertilization (How??)Internal fertilization (How??)

Fig. 7.29

I.Arthropoda B.Cirripedia (Barnacles) Active suspension feeders (filter feeders)Active suspension feeders (filter feeders) Use feathery cirri (modified swimming appendages)Use feathery cirri (modified swimming appendages) Sessile (attached to surfaces)Sessile (attached to surfaces) Fouling organisms (boats, whales)Fouling organisms (boats, whales) Resemble mollusks superficiallyResemble mollusks superficially Benthic forms also importantBenthic forms also important Some parasitic formsSome parasitic forms Simultaneous hermaphroditesSimultaneous hermaphrodites Internal fertilization (How??)Internal fertilization (How??)

I.Arthropoda C.Amphipoda (Amphipods) Laterally compressedLaterally compressed Generally small (< 2 cm), but larger in deep oceanGenerally small (< 2 cm), but larger in deep ocean Widespread distributionWidespread distribution Generally free livingGenerally free living Important scavengersImportant scavengers Often highly mobileOften highly mobile Some sedentary formsSome sedentary forms Diverse lifestylesDiverse lifestyles Brood youngBrood young

Fig. 7.30

I.Arthropoda D.Isopoda (Isopods) Dorsoventrally compressedDorsoventrally compressed Generally small (< 2 cm), but larger in deep oceanGenerally small (< 2 cm), but larger in deep ocean Related to terrestrial pill bugsRelated to terrestrial pill bugs Widespread distributionWidespread distribution Generally free livingGenerally free living Important scavengersImportant scavengers Often highly mobileOften highly mobile Some parasitic formsSome parasitic forms Brood youngBrood young

I.Arthropoda E.Euphausiacea (Krill) Laterally compressedLaterally compressed Up to 10 cm long (usually smaller)Up to 10 cm long (usually smaller) Head and anterior segments fused to form distinct carapaceHead and anterior segments fused to form distinct carapace Widespread distributionWidespread distribution Important primary consumers and predatorsImportant primary consumers and predators Important prey for larger consumersImportant prey for larger consumers Keystone species in some ecosystems (Southern Ocean)Keystone species in some ecosystems (Southern Ocean) Aggregate in schoolsAggregate in schools May be immense (450 sq km x 200 >1000 m -3 )May be immense (450 sq km x 200 >1000 m -3 )

I.Arthropoda F.Decapoda (Crabs, Lobsters, Shrimps) Most species in Crustacea (~10,000)Most species in Crustacea (~10,000) Scavengers/Predators/BothScavengers/Predators/Both Largest crustaceansLargest crustaceans Lobster > 42 lbsLobster > 42 lbs Crab > 10 feet “tall”Crab > 10 feet “tall” Five pairs of walking legsFive pairs of walking legs First pair usually modified as claws for feeding/defenseFirst pair usually modified as claws for feeding/defense Well-developed carapace = cephalothoraxWell-developed carapace = cephalothorax Rest of body = abdomenRest of body = abdomen Lobsters, shrimp – Usually laterally compressedLobsters, shrimp – Usually laterally compressed Tail/Abdomen behind thoraxTail/Abdomen behind thorax Crabs – Usually dorsoventrally compressedCrabs – Usually dorsoventrally compressed Tail/Abdomen curled underneath thoraxTail/Abdomen curled underneath thorax

Fig. 7.32

I.Arthropoda F.Decapoda (Crabs, Lobsters, Shrimps) Most species in Crustacea (~10,000)Most species in Crustacea (~10,000) Scavengers/Predators/BothScavengers/Predators/Both Largest crustaceansLargest crustaceans Lobster > 42 lbsLobster > 42 lbs Crab > 10 feet “tall”Crab > 10 feet “tall” Five pairs of walking legsFive pairs of walking legs First pair usually modified as claws for feeding/defenseFirst pair usually modified as claws for feeding/defense Well-developed carapace = cephalothoraxWell-developed carapace = cephalothorax Rest of body = abdomenRest of body = abdomen Lobsters, shrimp – Usually laterally compressedLobsters, shrimp – Usually laterally compressed Tail/Abdomen behind thoraxTail/Abdomen behind thorax Crabs – Usually dorsoventrally compressedCrabs – Usually dorsoventrally compressed Tail/Abdomen curled underneath thoraxTail/Abdomen curled underneath thorax

Shediac, NB

Fig. 7.37

I.Arthropoda G.Merostomata (Horseshoe crabs) Not true crabsNot true crabs Five living speciesFive living species Distinctive, horseshoe-shaped carapaceDistinctive, horseshoe-shaped carapace Benthic predators/scavengers on clams and small invertebratesBenthic predators/scavengers on clams and small invertebrates No jaws - Grind food with bristles on walking legs (must be walking to “chew”)No jaws - Grind food with bristles on walking legs (must be walking to “chew”)

I.Arthropoda H.Pycnogonida (Sea spiders) Superficially resemble spidersSuperficially resemble spiders Mouth at end of large proboscis (unusual)Mouth at end of large proboscis (unusual) CarnivoresCarnivores Feed on sea anemones, hydrozoans, other soft invertsFeed on sea anemones, hydrozoans, other soft inverts No respiratory or excretory systemsNo respiratory or excretory systems Digestive system extends into legsDigestive system extends into legs

Fig. 7.39

II.Echinodermata Radial symmetry (secondary)Radial symmetry (secondary) Bilateral symmetry in larvaeBilateral symmetry in larvae Pentaradial symmetry in adultsPentaradial symmetry in adults Oral/aboral - No anterior/posterior, dorsal/ventralOral/aboral - No anterior/posterior, dorsal/ventral Complete digestive tract (except Ophiuroidea)Complete digestive tract (except Ophiuroidea) EndoskeletonEndoskeleton Covered with layer of tissueCovered with layer of tissue Water vascular systemWater vascular system Unique to echinodermsUnique to echinoderms Tube feet extended by pressure from ampullaeTube feet extended by pressure from ampullae Tube feet used for locomotion, feeding, sensory functionsTube feet used for locomotion, feeding, sensory functions Connected to exterior through madreporiteConnected to exterior through madreporite

Fig. 7.42

II.Echinodermata A.Asteroidea (Sea stars) - Class Most species have five arms (some more)Most species have five arms (some more) Tube feet on oral surface in ambulacral groovesTube feet on oral surface in ambulacral grooves Endoskeleton composed of CaCO 3 platesEndoskeleton composed of CaCO 3 plates Flexible skeleton – permits movementFlexible skeleton – permits movement Aboral surface often covered with pedicellariaeAboral surface often covered with pedicellariae Small claws used for grooming surfaceSmall claws used for grooming surface PredatorsPredators Feed on bivalves, snails, barnaclesFeed on bivalves, snails, barnacles Pry shells of bivalve apart and insert stomachPry shells of bivalve apart and insert stomach

Heliaster helianthus

Crown of Thorns Acanthaster planci

II.Echinodermata B.Ophiuroidea (Brittle stars, Serpent stars) More species (~2000) than any other classMore species (~2000) than any other class Arms long and very flexibleArms long and very flexible May resemble writhing snakesMay resemble writhing snakes Tube feet lack suckers (used for feeding)Tube feet lack suckers (used for feeding) Cryptic – Usually not in open areasCryptic – Usually not in open areas Scavengers/DetritivoresScavengers/Detritivores Particles collected by tube feet and passed to mouthParticles collected by tube feet and passed to mouth May suspension feed by climbing on taller objects (e.g. sponges)May suspension feed by climbing on taller objects (e.g. sponges) Some have eyes and produce bioluminescenceSome have eyes and produce bioluminescence Why??Why??

Amphipholis squamata