Chapter 7 - Marine Invertebrates
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Transcript of Chapter 7 - Marine Invertebrates
CHAPTER 7
CHAPTER 7MARINE INVERTEBRATES
Marine Invertebrates Vertebrates: animals with a backboneInvertebrates: animals without a backboneAt least 97% of all species of animals are invertebrates
Sponges
SpongesSponges belong to the phylum Porifera or pore bearersaggregations of specialized cellsdo not form true tissues or organsnearly all marine
Spongessessile: living permanently attached to the bottom or some other surface
Sponges ostia: numerous tiny pores on the surface of the spongeallows water to enter and circulate through a series of canals where plankton and other organic matter are filtered out and eatensponge cells are very plasticif separated, the cells can even regroup and form a new sponge
Spongeswater is pumped into a larger feeding chamber lined with collar cells or choanocytes
water leaves through osculum: large opening on the top of the sponge
each choanocyte has a flagellum that creates currents and a thin collar that traps food, and then ingested by the body of the cellmost have many oscula
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Sponges
Spongesmost have spicules: transparent siliceous or calcareous supporting structures of different shapes and sizesmany have a skeleton of spongin: tough elastic fibers made of protein
these two are found mainly between the outer and inner layers of cells9
Spongesamoebocytes: wandering cells, that secrete spicules and spongin
also serve other uses such as food transport, food storage, cell repair and reproduction
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Spongessuspension feeders: animals that eat food particles suspended in waterfilter feeders: actively filter the food particles in the suspensiondeposit feeders: eat detritus that settles on the bottom
Sponges
SpongesMost produce asexuallybudding of new spongeSome use gemmules: survivor pods
SpongesFound almost everywhere in the worldlargest number are found in tropical watersencrusting sponges: form thin sometimes brightly colored growths on rocks or dead coral
Sponges Economic Importancebath spongesstill harvested in a few locations of the Gulf of Mexico and the eastern Mediterraneansome produce potentially useful chemicals
Cnidarians
CnidariansPhylum CnidariaAlso called coenlenteratesover 9,000 species including sea anemones, jellyfish, corals
Cnidariansdisplay radial symmetry: similar parts of the body are arranged and repeated around a central axislook the same from all sidesno head, front, or back
Cnidarianscnidocytes: specialized cells used mainly for capturing prey
Cnidariansoral surface: where the mouth is locatedaboral surface: located in the opposite site of the mouth
Cnidarians
Cnidarianscentrally located mouth surrounded by tentacles: slender finger-like extensions used to capture and handle foodmouth opens into a gut where food is digested
Cnidarianscapture food (small prey) by discharging nematocysts (or cnidae): unique stinging structures found within cells in the tentacles
CnidariansOccur in two basic forms - polyp or medusa
CnidariansPolyp: a sac-like attached stage with the mouth and tentacles oriented upwardsessileEx. sea anemone
CnidariansMedusa: Bell-like structure that resembles an upside-down polyp and is adapted for swimmingmotile, swimmingEx. jellyfish
Types of CnidariansHydrozoansScyphozoansAnthozoans
Hydrozoans (polyps)Feathery bushy colonies of tiny polypsdrifting colonies of hydrozoans are called siphonophores example: portuguese man-of-war (blue bubble or blue bottle) (Physalia physalis)
Portuguese Man-of-War
ScyphozoansTrue jellies with medusa shapes that can reach up to 6 feet in diameterTrue Nematocysts are only found in Hydrozoans and Scyphozoans
Anthozoanslack medusa stageconsists of solitary colonial polypsanemonescoralsseapenssea pansies
Bilaterally Symmetric Worms
Wormsbilateral symmetry: the arrangement of the body parts in such a way that there is only one way to cut the body and create two identical halvesex. humans
FlatwormsPhylum: Platyhelminthesdorsoventrally flattened (flat bellies and backs)20,000 species of flatworms
FlatwormsTurbellariansmost common marine flatwormsmainly live in or around the surface of other invertebrates (mollusks, crabs, etc)
FlatwormsFlukes (trematodes)largest group of flatworms6,000+ speciesall are parasites adults always live in a vertebratelarvae may inhabit invertebrates or smaller vertebrates such as fish
FlatwormsTapeworms (cestodes)parasiticlong body made of repeating unitslive in the intestines of vertebrates
Ribbon Worms (Nemertean Worms)Phylum: Nemerteaoutwardly resemble flatworms, slightly more complexmore advanced intestinal systemcirculatory systemproboscis: long fleshy tube used to entangle prey
can extend proboscis up to 1m beyond their bodyone species reaches 30m (100ft) making it the longest invertebrate on earth
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Nematodes (roundworms)Phylum: Nematodamost are parastic a layer of muscles in the body wall pushes and squeezes against the fluid creating a hydrostatic skeletonHydrostatic Skeleton: A system that uses water pressure against the body wall to maintain body shape and aid in locomotionprovide support and aids in locomotion
Nematodes (roundworms)live in the flesh or muscle tissue which used to make sashimi, sushi, and cervicheif the fish is served raw or undercooked, human infection is possible
most people immediately vomit the infected matter back up there are exceptions in which the larvae make it to the stomach or intestinecause symptoms similar to ulcerssevere pain, nausea, muscle tearing and sometimes bleeding
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Segmented Worms (annelids)Phylum: Annelidaearthworms and many marine wormsDisplay segmentationsegments act as a hydrostatic skeletonefficient crawlers and burrowers
can be contracted in sequence by body wall musclesthis and flexibility also given by segmentation makes annelids 41
Polychaetes (Bristle worms)Phylum: Annelida Class: Polychaetaeach body segment has a pair of flattened extensions called parapodia beyond/beside feetwhich have stiff, often sharp bristles called setaeUsed for movement and breathing through gills on parapodia
true circulatory systemmainly carnivorousseveral pairs of eyesa proboscis, often jawedmany polychaetes live in temporary or permanent tubes made of mucus, protein, seaweed, mud, sand or shell fragments
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Polychaetes (Bristle worms)
OligochaetesOligochaetessmall worms found in mud and sandfeed on detrituslack parapodia
OligochaetesLeechesClass: Hirudinealive mainly in fresh watermarine species can be found attached to marine fishes and invertebrateshighly specialized annelida with a sucker at each end and no parapodiaEchiuransall marinesimilar to peanut worms in size and shapehave a non-retractable, spoon-like (forked) proboscisdeposit feeders
Peanut Wormssipunculans1 to 35 cm long (.4 to 14 inches)soft unsegmented bodiesburrow in the bottom or move into empty shellswhen it becomes compact it resembles a large peanut
MolluscsClams, Octopuses, and Snails
MolluscsPhylum: Molluscamore species of mollusca than any other animal grouparound 200,000 living species
Molluscsmost have soft bodies encased in a calcium carbonate shelllive in marine, freshwater and terrestrial environments
Molluscscephalopods (squid, cuttlefish, octopus) most neurologically-advanced of all invertebratesgastropods (snails and slugs) are the most numerous divisiongiant or colossal squid are the largest known invertebrate species
MolluscsThe body is covered by a mantle: a thin layer of tissue that secretes the shellusually bilaterally symmetricventral, muscular foot usually used for locomotion
Molluscsmost have a head with eyes and additional sensory organsRadula: a ribbon of small teeth (unique to molluscs) or rasping tonguemade mainly of chitin
Molluscsgas exchange occurs through paired gillsshell is modified (internal for squid, octopod; external for gastropods)
Gastropods
Gastropodsclass - Gastropodalargest, most common, and most varied groupincludes snails, periwinkles, limpets, abalones
previously called univalvesgastropod literally means stomach footed
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Gastropodsa coiled collection of organs enclosed by a dorsal shellshell rests on a ventral footvaried shell structure and size
Gastropodscarnivorous gastropods prey on clams, oysters worms and even small fishesother gastropods are detritivores
GastropodsNudibranchs or sea slugs - gastropods that have lost their shell entirely
nudibranchs
Bivalves
Bivalvesclass - Bivalviaincludes clams, mussels, oysters, scallops
Bivalveshave two-part shells each part is called a valvesymmetric along the hinge lineno head no radulainner surface of the shell is lined by the mantle
Bivalvesgills are used for gas exchange and filter feedingstrong muscles in the mantle cavity are used to open and close the valves
OystersMost commercially valuable for pearlsForm when the oysters secrete layers of calcium carbonate coat an irritant or parasite lodges between the mantle and the inner surface of the shell
ClamsUse foot to bury in sand or mudDraw water in and out of mantle through siphonsFeed and maintain oxygen while still buried
MusselsLive mainly in the intertidal zoneAttach to surface using strong, byssal threads (beard)
ScallopsHighly prized food source100 simple blue eyes around the valves
Cephalopods
Cephalopodsclass-cephalopodaspecialized for locomotionadapted mollusc body plan for an active way of life (nearly all agile swimmers)include octopuses, squids, cuttlefish, nautilus
Cephalopodscomplex nervous systemreduced inner shell or no shell at allall are marine or brackishno radula, but do have a two part beak
Cephalopodsfoot is modified into arms and tentacleslarge eyes usually set on sides of the headthick, muscular mantle
Cephalopods2 to 4 gillswater enters through the free edge of the mantle and leaves through the siphon or funnel a muscular tube formed by what remains of the foot
Nautilus
Nautilus the chambered nautilus is considered the most primitive living cephalopod, because of its shelldates back 450 million years
Nautilus shell is thin, double layered and pearly white inside with a dull white with reddish zebra stripe outsidethe shell is separated into chambers by the septa, made of shell materialas it grows it creates new larger chambers1 chamber every few weeks until it reaches 38 chambers
Nautilusoccupies one body chamberstrong, beak-shaped crushing jawseat algae , fish, crabs, shrimp and other invertebrates
Nautiluslarge collection of tentacles arranged into two circles, an inner and an outer.the female has twice as many tentacles in its inner circle than the male
Squid
Squidhas only a thin shell remnant (pen) within its mantlestrengthened outer collagen sheath to maintain the mantles shape and size
Squidto swim, the squid fills the mantle cavity with water and then forces it outward through the funnel in a jet-propulsion like manner normally swims backwards, can swim forward by bringing all 8 arms together
Humboldt Squid
Squidfins along the body help with stabilizationlarge squids can reach speeds of 15-20 mphmany species swim in schools
Squid8 arms, 2 long tentacles covered in suckers: adhesive discs used for suction between the squid an another objecttentacles only have suckers on the flattened end
Octopus
Octopushas lost shell entirelybag-like mantle located above the headalso has a strengthened collagen sheath surrounding the mantle
Octopusdoes not normally swimprefers to remain in contact with a solid surfaceuses suckers on its 8 legs to push and pull itself along the surfacemost have 240 suckers on each armCrawling
Octopususually a solitary animal that lives in a permanent den or cave under rocksinkchromatophores: specialized cells used to help an organism change colorChromatophores in action
Cephalopod Feeding and Digestion
Feeding and Digestion separate mouth and anusall cephalopods are carnivoresinvolves salivary and digestive glands to help break down foodvaried diets and complexity of digestive systems based on diet
Hungry octopus
Feeding and Digestioncrystalline style: an enzyme secreting rod found in the stomach of bivalves continually rotates food and helps in digestion
Feeding and Digestion most molluscs have an open circulatory systemcephalopods have a closed circulatory system
Nervous System and Behaviors
Nervous Systemgastropods and bivalves do not have a single brain but several sets of gangliacephalopods most complexallows for learning to occurand for rapid movement and color changing to avoid predation
clusters of local brainslarger brainlarge never fibers that extend the length of the body
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Reproduction
Reproductionmost reproduce sexually, some hermaphroditiccephalopods use a spermatophorecephalopods lack larva and have large yolk-filled eggsoctopus protect eggs and female usually dies protecting young because she does not leave to eat herself
Reproduction
Octopus mating
Arthropods
ArthropodsPhylum: Arthropodalargest phylum of animalsinsects are dominant terrestrial groupcrustaceans are more common in marine environments
Arthropodssegmented, bilaterally symmetricpossess an exoskeleton: large, non-living external skeletoncomposed of chitin and secreted by the underlying layer of tissue
Arthropodsprovides protection, support and increased surface area for muscle attachmentto grow, arthropods must molt
Crustaceans
Crustaceanschitinous skeleton hardened by calcium carbonateappendages specialized for swimmingpossess 2 pairs of antennae
Small Crustaceans - Copepodssmall, important to planktonuse enlarged pair of antennae for swimmingmany are parasitic
Small Crustaceans - Barnaclesfilter feederslive attached to surfaces, including other living organismscovered in calcareous plateshave feather-like filtering appendages called cirriactually legs used to sweep water
Small Crustaceans Amphipods small curved body and flattened sidewaysless than 2 cm in lengthsome live under larger organisms skin like lice, parasites
Small Crustaceans - Isopodsabout the same size amphipodsdorsoventrally flattenedex. terrestrial pill bugsmany are parasitic
Small Crustaceans - KrillAlso called euphausidsplanktonic, shrimp-likeup to 6 cm long (2.5 in)most are filter feedersswim in groups of billions of individuals
Decapodsfive pairs of legs or pereiopodsthe first is heavier - usually claws for feeding and defense
Decapodsthree pairs of maxillipeds near the mouthturned forward, and specialized to sort food and push it towards the mouth
Decapodswell developed carapaceencloses the part of the body called the cephalothoraxthe rest of the body is known as the body
Decapodsshrimp and lobsters have laterally compressed bodies with distinct and elongated abdomens (the tail)
DecapodsDecapods use their chelipeds for feeding and fightingTherefore they often lose a clawThey are able to regenerate lost chelipeds
DecapodsAlso most arthropods have two distinct clawsThe larger is called the crusher clawAnd the thinner, more serrated one, is called the pincer or tearing claw
DecapodsIn many arthropods, such as lobsters, there are major structural difference between males and females1. Claw size (larger in males)2. Tail width (wider in females)3. Texture of swimmerets (harder in males)
DecapodsReproduce sexually, using internal fertilization
DecapodsAlso in crabs, a male has a v shaped abdomen and a female has a u shaped abdomen
ShrimpTypically scavengersVaried life environmentsMutualistic relationships with other organisms
Shrimp 1Shrimp 2
American Lobster (Homarus americanus)also known as the northern lobster, Atlantic lobster or Maine lobsterfamily Nephropidae, commercial lobstersbottom dwellerfound in colder waters off the Atlantic coast of North AmericaNew England and Canada
Lobstersscavenger and predatorsolitary in rocks or caves, also nocturnalexoskeleton, which molts 2-3 times a year as a juvenile and once a year as an adult
Blue Lobster Molt
LobstersHeavy bodied with a large abdomen and huge chelipedsone is lost in an accident or a fight it will regeneratesold with one claw -cull Sold with no claws bullet
Lobsters4 pairs of walking legs (pereiopods)4 sets of swimmerets (pleopods), extend across the bodyharder in malessofter in females used to protect eggs
Lobstersfeathery gills located on either side of the cephalothorax
Hermit Crabs
hermit crabs are not true crabs scavengershide in empty gastropod shells
Crabsabdomen is small and tucked under a compact and broad cephalothoraxlargest and most diverse group of decapods
Crabshighly mobile - much faster than lobstersmove sideways when theyre in a hurrysideways movement can also be used to indicate matingex. fiddler crab
Horseshoe Crabsnot true crabsliving fossilseyes being researched to improve vision errors in humans
Sea spiders
Lophophorates
LophophoratesHave a lophophore - feeding structure made of a set of ciliated tentacles arranged in a horseshoe-like shape
LophophoratesThree main types:Bryozoans - lace-likePhoronids - worm-likeLamp Shells - clam-like
Echinoderms
EchinodermsPhylum: EchinodermataPentamerous Radial symmetry: Five-way symmetry
EchinodermsWater-vascular system: A network of water-filled canalssea stars sea urchins connect to a madreporite: a porous plate on the aboral surface
EchinodermsTube feet: muscular extensions of the water-vascular system that often end in a suckerampullae: muscular sacs that sometimes aid in the extension of tube feet
Echinodermssmall nerve net similar to cnidariansability to regenerateComet: a sea star with one large regenerated arm
Echinodermsmany spines and bumps - part of the endoskeletongive the nickname spiny-skinned
EchinodermsFour main types:Sea starsBrittle StarsSea CucumbersSea Urchins
Sea StarsClass: Asteroideafive arms that radiate around a central disk
Sea Starshundreds of tube feet extend from the oral surface along radiating channels on each arm call ambulacral grooves
Sea Starsthe aboral surface of most sea stars is covered with spines modified into pincer like organs called pedicellariaemost are predators of bivalves
Brittle StarsClass: Ophiuroideastar shaped bodyvery long flexible armslack an anusare detritivores
Sea CucumbersClass: Holothuroideasuperficially wormlikelack spinesno radial symmetry
Sea Cucumbersoral and aboral surfaces are located on the endsdeposit feedersmove using five rows of tube feetuse branched tentacles to gather food
Sea Cucumbersdefensesome secrete toxic substancessome discharge, sometimes toxic, filaments from the anus to discourage predatorssome eviscerate: discharge the gut and other organs through the anus
Sea Urchinsendoskeleton is round and rigid with movable spines and pedicellariaemovement is based on tube feet and the movable spines joined to sockets of the exoskeleton
Sea Urchinsgrazers - sea weeds and grassesmouth has an intricate system of jaws and muscles called aristotles lanternused to bite off pieces
Sea Urchinslive in rocky shoresalso includes sand dollars
Chordates Without a Backbone
Chordates without a backbonePhylum Chordatadivided into three major groups (subphyla)two lack a backbone, one does notProtochordates: the invertebrate chordates, chordates without a backbone
Chordates without a backbone4 characteristics needed to be a chordate:1. single, hollow nerve chord that runs along the dorsal side of the body
Chordates with a backbone2. pharyngeal gill slits - small openings along the anterior end of the gutpharynx in humans
Chordates without a backbone3. notochord - flexible rod for support that lies between the nerve chord and the gut
Chordates Without a Backbone4. post-anal tail - a tail that extends beyond the anus (coccyx in humans)
Chordates without a backbone
Chordates without a backbone
Chordates without a backbonealso have a ventral heartin vertebrates the notochord is replaced by the backbone (vertebral column)
Tunicates
TunicatesSubphylum: Unichordatabest known are sea squirtsthe notochord and tail are absorbed during metamorphosis
Tunicatesdifference between sponge is the protective tunictunic: leathery or gelatinous outer covering not found on spongesfilter feeders
Lancelets
LanceletsSubphylum Cephalochordataalmost 3 in longlaterally compressed and elongated body like a fishbottom dwellersfilter feeders