I.Nematoda Free living and parasitic formsFree living and parasitic forms Cosmopolitan/UbiquitousCosmopolitan/Ubiquitous Mostly in sediments (free living) or hosts (parasitic)Mostly in sediments (free living) or hosts (parasitic) Common in fine mudsCommon in fine muds Organic rich areasOrganic rich areas Described species – 12,000+Described species – 12,000+ May be up to 500,000 species total!May be up to 500,000 species total! Extremely abundant!!Extremely abundant!! Up to hundreds of individuals per ml of sedimentUp to hundreds of individuals per ml of sediment 90,000 in one rotting apple (not marine)90,000 in one rotting apple (not marine) Hydrostatic skeletonHydrostatic skeleton Longitudinal muscles onlyLongitudinal muscles only Move by whipping back and forthMove by whipping back and forth
II.Other Worms A.Sipuncula (Peanut worms) Exclusively marine (250+ species)Exclusively marine (250+ species) Most common in shallow waterMost common in shallow water Unsegmented bodies up to 35 cm longUnsegmented bodies up to 35 cm long Studded introvert used for locomotionStudded introvert used for locomotion CrypticCryptic Burrow in sediments or hide in sheltersBurrow in sediments or hide in shelters Deposit feedersDeposit feeders Consume detritus and microbesConsume detritus and microbes
II.Other Worms A.Sipuncula (Peanut worms) Exclusively marine (250+ species)Exclusively marine (250+ species) Most common in shallow waterMost common in shallow water Unsegmented bodies up to 35 cm longUnsegmented bodies up to 35 cm long Studded introvert used for locomotionStudded introvert used for locomotion CrypticCryptic Burrow in sediments or hide in sheltersBurrow in sediments or hide in shelters Deposit feedersDeposit feeders Consume detritus and microbesConsume detritus and microbes
Fig. 7.3
II.Other Worms B.Echiura (Spoon worms) Exclusively marine (~150 species)Exclusively marine (~150 species) Deposit feedersDeposit feeders Feed with non-retractable proboscisFeed with non-retractable proboscis Live in burrowsLive in burrows U-shaped or L-shapedU-shaped or L-shaped Typically small but may get large in deep seaTypically small but may get large in deep sea
II.Other Worms C.Pogonophora (Beard worms) Long, thin worms (~135 species)Long, thin worms (~135 species) Most common in deep seaMost common in deep sea No mouth or gutNo mouth or gut Not parasiticNot parasitic Anterior end of body is tuft of up to several thousand tentaclesAnterior end of body is tuft of up to several thousand tentacles Tentacles absorb dissolved nutrientsTentacles absorb dissolved nutrients Symbiotic bacteria utilize nutrients to manufacture foodSymbiotic bacteria utilize nutrients to manufacture food VestimentiferaVestimentifera Large deep-sea animalsLarge deep-sea animals Found at many hydrothermal ventsFound at many hydrothermal vents
Fig. 7.17
II.Other Worms C.Pogonophora (Beard worms) Long, thin worms (~135 species)Long, thin worms (~135 species) Most common in deep seaMost common in deep sea No mouth or gutNo mouth or gut Not parasiticNot parasitic Anterior end of body is tuft of up to several thousand tentaclesAnterior end of body is tuft of up to several thousand tentacles Tentacles absorb dissolved nutrientsTentacles absorb dissolved nutrients Symbiotic bacteria utilize nutrients to manufacture foodSymbiotic bacteria utilize nutrients to manufacture food VestimentiferaVestimentifera Large deep-sea animalsLarge deep-sea animals Found at many hydrothermal ventsFound at many hydrothermal vents
III. Annelida Segmented wormsSegmented worms Body composed of repeated segmentsBody composed of repeated segments Gut runs through all segments in body cavity (coelom)**Gut runs through all segments in body cavity (coelom)** Coelom filled with fluid – hydrostatic skeletonCoelom filled with fluid – hydrostatic skeleton Longitudinal and radial musclesLongitudinal and radial muscles Efficient locomotion and burrowingEfficient locomotion and burrowing More than 15,000 speciesMore than 15,000 species CosmopolitanCosmopolitan
III. Annelida A.Polychaeta 10,000+ species (mostly marine)10,000+ species (mostly marine) Body segments bear pairs of parapodiaBody segments bear pairs of parapodia Parapodia used for locomotion, feedingParapodia used for locomotion, feeding Often tipped with setaeOften tipped with setae Closed circulatory system**Closed circulatory system** Efficient transport of blood, gasesEfficient transport of blood, gases Gas exchangeGas exchange Small species exchange gases across body wallSmall species exchange gases across body wall Large species have gills for gas exchangeLarge species have gills for gas exchange Highly vascularized with capillaries and thin body wallsHighly vascularized with capillaries and thin body walls
Fig. 7.15
III.Annelida A.Polychaeta Spawning – Palolo wormSpawning – Palolo worm Larva = TrochophoreLarva = Trochophore Band of cilia around body; tuft on apexBand of cilia around body; tuft on apex Same larval stage in Mollusca, Echiura, SipunculaSame larval stage in Mollusca, Echiura, Sipuncula Diverse lifestylesDiverse lifestyles Free-living predatorsFree-living predators Often well-developed eyes and sense organs, jawsOften well-developed eyes and sense organs, jaws Burrowing deposit feedersBurrowing deposit feeders Burrowing suspension feedersBurrowing suspension feeders Tube building suspension feedersTube building suspension feeders Tubes may be calcium carbonate, agglutinated or parchmentTubes may be calcium carbonate, agglutinated or parchment SolitarySolitary ColonialColonial
III.Annelida A.Polychaeta Larva = TrochophoreLarva = Trochophore Band of cilia around body; tuft on apexBand of cilia around body; tuft on apex Same larval stage in Mollusca, Echiura, SipunculaSame larval stage in Mollusca, Echiura, Sipuncula Diverse lifestylesDiverse lifestyles Free-living predatorsFree-living predators Often well-developed eyes and sense organs, jawsOften well-developed eyes and sense organs, jaws Burrowing deposit feedersBurrowing deposit feeders Burrowing suspension feedersBurrowing suspension feeders Tube building suspension feedersTube building suspension feeders Tubes may be calcium carbonate, agglutinated or parchmentTubes may be calcium carbonate, agglutinated or parchment SolitarySolitary ColonialColonial
III.Annelida A.Polychaeta Larva = TrochophoreLarva = Trochophore Band of cilia around body; tuft on apexBand of cilia around body; tuft on apex Same larval stage in Mollusca, Echiura, SipunculaSame larval stage in Mollusca, Echiura, Sipuncula Diverse lifestylesDiverse lifestyles Free-living predatorsFree-living predators Often well-developed eyes and sense organs, jawsOften well-developed eyes and sense organs, jaws Burrowing deposit feedersBurrowing deposit feeders Burrowing suspension feedersBurrowing suspension feeders Tube building suspension feedersTube building suspension feeders Tubes may be calcium carbonate, agglutinated or parchmentTubes may be calcium carbonate, agglutinated or parchment SolitarySolitary ColonialColonial