what are animals? animals: 1. are multicellular – distinguishes them from bacteria and most...
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What Are Animals? Animals:
1. are multicellular– distinguishes them from bacteria and most
protists
2. have eukaryotic cells without cell walls– distinguishes them from bacteria, fungi, algae
and plants
3. cannot produce their own food, so they depend on other organisms for nutrients
4. can actively move (with the exception of adult sponges)
SpongesPhylum PoriferaBasic characteristics:
simpleasymmetricsessile—permanently attached to a solid
surfacehave many shapes, sizes and colors
Sponge Structure and FunctionBody is built around a system of water canals
ostia—tiny holes or pores through which water enters the sponge’s body
spongocoel—spacious cavity in the spongeosculum—large opening through which water
exits from the spongocoel
Sponge Structure and FunctionLacking tissues, sponges have specialized
cellscollar cells (choanocytes) use their flagella to
provide force for moving water through the sponge’s body
archaeocytes—cells that resemble amoebas, and can move through the body can assume any of the other cell forms, or transport
materials
Sponge Structure and FunctionStructural materials
spicules—skeletal elements that give support to a sponge’s body, which are produced by specialized cells and composed of calcium carbonate, silica or spongin
spongin—a protein that forms flexible fibers
Sponge Structure and FunctionSponge size and body form
size is limited by water circulationasconoid—simplest form; tubular and always
smallsyconoid—sponges that exhibit the first stages
of body-wall foldingleuconoid—sponges with the highest degree of
folding, which have many chambers lined with collar cells
Sponge Structure and FunctionNutrition and digestion
sponges are suspension feeders – they feed on material that is suspended in seawater
sponges are filter feeders – they filter their food from the water
sponges are one of the few animals that can capture particles 0.1 to 1.0 micrometers in size
Sponge Structure and FunctionReproduction in sponges
asexual reproduction budding—a group of cells on the outer surface of
the sponge develops and grows into a tiny new sponge, which drops off
fragmentation—production of a new sponge from pieces that are broken off
sexual reproduction eggs usually develop from archaeocytes and sperm
from modified collar cells larval stage is a planktonic amphiblastula
Ecological Roles of SpongesCompetition
compete for space to attach with corals and bryozoans
Predator-prey relationshipsfew species eat sponges
spicules are like needles some produce chemical deterrents
major food source for hawksbill sea turtle
Ecological Roles of SpongesSymbiotic relationships
sponges are mutualistic or commensalistic hosts to many organisms e.g. mutualistic bacteria
many organisms live within the canals or spongocoel, for protection, water flow
Sponges and nutrient cyclingboring sponges recycle calcium as they burrow
into coral and mollusc shells
Cnidarians: Animals with Stinging CellsPhylum CnidariaNamed for their cnidocytes—stinging cellsCnidocytes are used to capture prey and
protect the animal
Organization of the Cnidarian BodyRadial symmetry—many planes can be drawn
through the central axis that will divide the animal into equivalent halves
Often exhibit 2 body plans within their life cycles:polyp—a benthic form characterized by a
cylindrical body with an opening at 1 endmedusa—a free-floating stage (jellyfish)
Stinging CellsCnida—stinging organelle within a cnidocyte,
which may function in locomotion, prey capture, or defensenematocysts—spearing type, which are
discharged when the cnidocill—a bristle-like trigger—contacts another object
Dangerous speciesPortuguese man-of-war (painful stings)box jellyfish (can kill within 3-20 minutes)
Types of CnidariansHydrozoans (class Hydrozoa)
mostly colonialcolonial forms contain 2 types of polyp:
feeding polyp—functions in food capture reproductive polyp—specialized for reproduction
hydrocorals secrete a calcareous skeletonsome produce floating colonies
e.g. Portuguese man-of-war
Types of CnidariansScyphozoans
true jellyfish (class Scyphozoa) medusa is predominant life stage photoreceptors—sense organs that can determine
whether it is dark or light
Cubozoabox jellyfish (class Cubozoa)
tropical voracious predators, primarily of fish
Types of CnidariansAnthozoans (class Anthozoa)
sea anemones polyps with a vascular cavity divided into
compartments radiating from the central one though sessile, many can change locations
coral animals polyps that secrete a hard or soft skeleton form reefs along with types of algae
soft corals polyps that form plant-like colonies
Nutrition and Digestion of CnidariansGastrovascular cavity—central cavity where
cnidarians digest their preyfunctions in digestion and transport
Many hydrozoans and anthozoans are suspension feeders
Jellyfish and box jellyfish eat fish and larger invertebrates
Sea anemones generally feed on invertebrates
ReproductionHydrozoans
generally exhibit asexual polyp stage and sexual medusa stage in the life cycle
reproductive polyps form medusa-like buds which grow into adults after release
adults release gametes into the water, where they are fertilized and form larvae planula larva—planktonic larva that grows in the
water column, then settles
ReproductionScyphozoans
medusae (sexual stage) release gametes into the water for fertilization
planula larvae settle, grow into polyps, and reproduce medusa-like buds asexually
ReproductionAnthozoans
asexual reproduction pedal laceration—leaving parts of the pedal disk
(base) behind to grow into new animals fission—the anemone splits in two and each half
grows into a new individual budding produces large colonies of identical hard
coralssexual reproduction
larval stage is a planula larva
Ecological Relationships of CnidariansPredator-prey relationships
cnidarians are predatorsstinging cells discourage predation
Habitat formationcoral polyps form complex 3-dimensional
structures inhabited by thousands of other organisms
coral reefs provide a solid surface for attachment, and buffer waves and storms
Ecological Relationships of CnidariansSymbiotic relationships
Portuguese man-of-war and man-of-war fishreef-forming corals and zooxanthellaesea anemones...
and clownfish and the hermit crab
CtenophoresPhylum CtenophoraPlanktonic, nearly transparentCtenophore structure
named for 8 rows of comb plates (ctenes) which the animal uses for locomotion ctenes are composed of large cilia
exhibit radial symmetrybioluminescent
CtenophoresDigestion and nutrition
carnivorous, feeding on other planktonic animals
may used branched tentacles in a net pattern, adhesive cells, jellyfish stingers
Coral AnimalsStony (true) corals deposit massive
amounts of CaCO3 that compose most of the structure of coral reefs
Hermatypic—coral species that produce reefs, found in shallow, tropical waters
Ahermatypic—corals that do not build reefs, which can grow in deeper water from the tropics to polar seasmost do not harbor zooxanthellae
Coral AnimalsCoral colonies
large colonies of small coral polyps, each of which secretes a corallite
a planula larva settles and attachesa polyp develops, and reproduces by budding
to form a growing colonypolyps’ gastrovascular cavities remain
interconnecteda thin, usually colorful epidermis overlies the
colony surface
Coral AnimalsSexual reproduction in coral
mostly broadcast spawners—release both sperm and eggs into the surrounding seawater
spawning is usually synchronous among Pacific reef species, but nonsynchronous among Caribbean species
Coral AnimalsAsexual reproduction
Reproduction by fragmentation some branching corals are fragile and tend to break
during storms if they survive the storm, fragments can attach and
grow into new colonies fragmentation is a common form of asexual
reproduction for branching corals
Coral AnimalsCoral nutrition
symbiotic zooxanthellae supply 90% of nutritional needs of stony coral zooxanthella provide glucose, glycerol and amino
acids coral polyp provides a suitable habitat and
nutrients, absorbed directly through the animal’s tissues
zooxanthellae remove CO2 and produce O2
need of zooxanthellae for sunlight limits depths to which stony corals can grow
Coral AnimalsCoral nutrition (continued)
corals as predators small animals paralyzed by the nematocysts are
passed into the digestive cavity
World of Coral ReefsCoral reefs are highly productive, but occur
in nutrient-poor watersThis is made possible by the symbiotic
relationship between coral animals and zooxanthellae
These symbionts + algae form the basis of the community; other reef animals depend on these organisms
Coral Reef TypesFringing reefs border islands or continental
landmassesBarrier reefs are similar to fringing reefs but
separated from the landmass and fringing reef by lagoons or deepwater channels
Atolls, usually elliptical, arise out of deep water and have a centrally-located lagoon
Reef StructureReef front or forereef—portion of the reef
that rises from the lower depths of the ocean to a level just at or just below the surface of the water, on the seaward sidedrop-off—a steep reef-front that forms a
vertical wallspur-and-groove formation or buttress zone—
finger-like projections of the reef front that protrude seaward; disperses wave energy and helps prevent damage
Reef StructureReef crest—the highest point on the reef and
the part that receives the full impact of wave energywhere wave impact is very strong, it may
consist of an algal ridge of encrusting coralline algae, lacking other organisms, and penetrated by surge channels—grooves of the buttress zone
Reef flat or back reef—portion behind the reef crest
Coral Reef DistributionMajor factors influencing distribution:
temperature – corals do best at 23-25o Clight availability – photosynthetic zooxanthellae
need lightsediment accumulation – can reduce light and
clog feeding structuressalinitywave action – moderate wave action brings in
oxygenated seawater, removes sediment that could smother coral polyps
duration of air exposure – can be deadly
Reef ProductivitySource of nutrients
land runoff for reefs close to landsource for atolls unclearpossible explanations:
nutrients accumulated over time are efficiently recycled
reef bacteria and filter feeders capitalize on nutrients from dissolved/particulate organic matter
nutrients brought from other communities
Reef ProductivityReef photosynthesis
photosynthetic organisms: zooxanthellae, benthic algae, turf algae, sand algae, phytoplankton, seagrasses
Coral Reef CommunitySponges and cnidarians
sessile organisms, though anemones can move if necessary
filter feed; anemones also paralyze and consume small fishes and crustaceans
Annelidssessile filter feeders include featherduster and
Christmas tree wormsfireworms are mobile predatorspalolo worms burrow through and weaken
coral and usually deposit feed
Coral Reef CommunityCrustaceans
shrimps, crabs and lobstersvary from parasites to active hunters
Molluscsgastropods eat algae from coral surfacesgiant clams are filter feeders, but also host
symbiotic zooxanthellaeoctopus and squid are active predators
Coral Reef CommunityEchinoderms
feather stars, sea urchins, brittle stars, sea stars, and sea cucumbers
filter feed, scavenge, or eat sedimentReef fishes
most prominent and diverse inhabitantdiverse food sources, including detritus, algae,
sponges, coral, invertebrates, other fish
Species Interactions on Coral ReefsCompetition between corals and other reef
organisms for space to attachEffect of grazing
grazing of larger, fleshier seaweeds permits competitively inferior filamentous forms or coralline algae to persist
herbivory decreases with depth
Species Interactions on Coral ReefsEffect of predation
predation of sponges, soft corals and gorgonians provides space for competitively inferior reef corals
species that feed on fast-growing coral assist slower-growing species to remain
corallivores seldom destroy reefssmall invertebrates are almost all well hidden
or camouflaged, indicating the prevalence of predation in the reef
Coral Reef EcologyCoral provides:
foundation for reef food websshelter for resident organisms
Reefs form a complex 3-dimensional habitat for many beautiful and strange creatures
Threats to Coral ReefsEffect of physical changes on the health of
coral reefshurricanes and typhoons topple and remove
coral formationsEl Niño Southern Oscillation (ENSO)
changes winds, ocean currents, temperatures, rainfall and atmospheric pressure over large areas of tropical and subtropical areas
can cause massive storms
Threats to Coral ReefsCoral bleaching
a phenomenon by which corals expel their symbiotic zooxanthellae
most often associated with warming of the ocean water by ENSO or global warming
if the stress is not too severe, corals may regain zooxanthellae and recover
if the stress is prolonged, corals may fail to regain zooxanthellae and die
Threats to Coral ReefsCoral diseases
black band disease—a distinct dark band of bacteria migrates across the living coral tissue, leaving behind a bare white skeleton
white pox—characterized by white lesions and caused by Serratia marcescens
other coral diseases: white band disease white plague yellow blotch disease
Threats to Coral ReefsHuman impact on coral reefs
overfishing may occurhuman-sewage bacteria cause white poxnutrient-rich runoff (eutrophication) increases
algal growth, which covers and smothers corals e.g. Kane’ohe Bay in Hawaii
Evolutionary Adaptations of Reef DwellersProtective body covering
tough, defensive exteriors help animals avoid predation, but can limit mobility and growth
Protective behaviorsproducing a poisonous coating of mucusburying the body in sand to hideinflating to appear largerhiding at night when nocturnal predators are
active
Evolutionary Adaptations of Reef DwellersRole of color in reef organisms
color for concealment and protection countershading disruptive coloration camouflage (bright colors in reef environment)
Evolutionary Adaptations of Reef DwellersRole of color in reef organisms
other types of camouflage body shape
warning colorationother roles of color
defending territories mating rituals
Evolutionary Adaptations of Reef DwellersSymbiotic relationships on coral reefs
cleaning symbioses cleaner wrasses, gobies, etc. feed on parasites of
larger fishes cleaning organisms set up a cleaning station
Other symbiotic relationships clownfishes and anemones conchfish and the queen conch gobies and snapping shrimp crustaceans and anemones
MolluscsPhylum MolluscaHave soft bodies, usually covered by a
calcium carbonate shellOne of the largest and most successful
groups of animalsWide range of sizes, lifestyles and
relationships to humans (i.e., some are food, others cause commercial damage)
Ex: Snails, Clams, Squid, Octopus
Molluscan Body2 major parts (mostly for snails and
nudibranchs):head-foot—region containing the head with its
mouth and sensory organs and the foot, which is the animal’s organ of locomotion
visceral mass—body region containing the other organ systems, including the circulatory, digestive, respiratory, excretory and reproductive systems
Molluscan BodyMantle—protective tissue covering the soft
parts, which extends from the visceral mass and hangs down on each side of the body; it forms the shell
Radula—a ribbon of tissue containing teeth (found in all except bivalves) used for scraping, piercing, tearing or cutting pieces of food
Molluscan ShellSecreted by the mantleNormally comprises 3 layers:
periostracum—outermost layer, composed of the protein conchiolin that protects the shell from dissolution and boring animals
prismatic layer—middle layer, composed of calcium carbonate and protein, which makes up the bulk of the shell
nacreous layer—innermost layer, composed of calcium carbonate in thin sheets, with a different crystal structure
Molluscan ShellPeriostracum and prismatic layers form at
the mantle’s margin as the animal growsNacreous layer is secreted continuously
nacreous layer of oysters is known as mother of pearl, which can become layered over irritating particles (such as sand grains) to form pearls
Chitons (class of mollusca)Class PolyplacophoraHave flattened bodies most often covered by
8 shell platesAttach tightly to rocksMost scrape algae and other organisms off
the rocks with radulae for food
Scaphopods (class of mollusca)Tusk shells (class Scaphopoda)Tusk-like shell is open at both ends, with foot
protruding from larger endWater enters and exits at smaller endFeed primarily on foraminiferans, which are
captured with the foot or tentacles emerging from the head
Gastropods (class of mollusca)Class Gastropoda (snails and nudibranchs)May have no shell, or a univalve (one-piece)
shellas the animal grows, whorls of the shell
increase in size around a central axisoperculum—covering over the shell’s aperture
which allows it to be closed
GastropodsFeeding and nutrition
herbivores – most feed on fine algae; some on large algae like kelps
carnivores – usually locate prey using its chemical trail; have evolved various behaviors for capturing/subduing prey
scavengers and deposit feedersfilter feeders
GastropodsNaked gastropods
nudibranchs—marine gastropods that lack a shell
have cerata—projections from the body that increase the surface area available for gas exchange
some feed on cnidarians and then use their stinging cells as defensive weapons in the tips of cerata
bright colors indicate toxicity to predators
Bivalves (class of mollusca)Class BivalviaHave shells divided into 2 jointed halves
(valves)Includes:
clamsoystersmusselsscallopsshipworms
BivalvesBivalve anatomy
no head or radulalaterally compressed bodies shell halves attached dorsally at a hinge by
ligaments umbo—oldest part of the shell, around hinge adductor muscles—large muscles which close the 2
valvesmantle often forms inhalant and exhalant
openings to facilitate filter feeding palps form the food into a mass for digestion
Cephalopods (class of mollusca)Class Cephalopoda (nautilus, squid, cuttlefish, octopus)
Ring of tentacles projects from the anterior edge of the head, for use in prey capture, defense, reproduction and sometimes locomotion
Except for nautiloids, they lack shells or have small internal shells
CephalopodsTypes of cephalopods
nautiloids produce large, coiled shells composed of chambers
separated by septa (partitions) gas-filled chambers aid with buoyancy siphuncle—cord of tissue connecting the nautiloid to
uninhabited chambers (it inhabits the last chamber) which removes seawater from each chamber as it forms
60-90 tentacles coated with a sticky substance function in sensation or bringing food to the mouth
Cephalopodsnautiloids (continued)
move using jet propulsion usually dwell on the bottom during the day and
migrate to the surface at night nautiloids eat hermit crabs and scavenge for other
food on the bottom food is stored in a crop prior to transport to the
stomach for digestion
Cephalopodscoleoids (e.g. cuttlefish, squids, octopods)
cuttlefish have a bulky body, fins, 10 appendages (8 arms + 2 tentacles), and small internal shells
squids have: large cylindrical bodies with a pair of fins derived
from mantle tissue 10 appendages (8 arms + 2 tentacles) arranged in 5
pairs around the head and embellished with cup-shaped suckers surrounded by toothed structures and attached by a short stalk
a pen (a degenerate shell; an internal strip of hard protein) which helps support the mantle
Cephalopodscoleoids (continued)
octopods have 8 arms (no tentacles) with suckers without stalks or teeth, and sac-like bodies without fins
coleoids cloud the water with a dark fluid called sepia containing melanin (a brown-black pigment) when disturbed
swim by jet propulsion by forcing water through a ventrally-located siphon or by fin undulation (in squids)
have the most advanced, complex nervous system among invertebrates
CephalopodsColor and shape in cephalopods
arm/body movements and color changes are used in communication
chromatophores—special skin cells containing pigment granules which are concentrated or dispersed to change color
cephalopods can produce general body color changes or stripes and other patterns
CephalopodsFeeding and nutrition
carnivores – prey is located with highly developed eyes and captured by tentacles or arms
a pair of powerful, beak-like jaws in the oral cavity is used to bite or tear tissues; octopods use radula to drill holes in shells
diet depends on habitat squids are pelagic: fish, crustaceans, squid cuttlefish find invertebrates on the bottom octopods forage or lie in wait near the entrances to
their dens
CephalopodsReproduction in cephalopods
sexes are separatemating frequently involves some kind of
courtship displaymale squid have a modified arm used to
transfer a spermatophore (sperm package) from his mantle cavity to the female’s, near the opening of the oviduct (tube that carries eggs to the outside of the body)
Ecological Roles of MolluscsFood for humans and other animals
snail shells are a calcium source for some marine birds
sperm whales consume masses of squidSome snails are intermediate hosts to parasitesShipworms damage wooden pilings and boat
hulls, but also prevent wood from accumulating in the marine environment
A few bivalves have commensal relationships (attaching to other animals)
Arthropods: Animals with Jointed AppendagesPhylum Arthropoda = 75% of species
Ex: crabs, lobsters, shrimp, crawfishHave exoskeleton—a hard, protective exterior
skeleton composed of protein and chitin (a tough polysaccharide)molting—shedding and replacement of
exoskeleton to permit animal’s growthBody is divided into segmentsUsually, each segment has a pair of jointed
appendages, for locomotion, mouthparts, sensation, ornamentation
Arthropods: Animals with Jointed AppendagesHave highly developed nervous systems
sophisticated sense organscapacity for learning
2 major groups of marine arthropods:chelicerates – have a pair chelicerae (oral
appendages) and lack mouthparts for chewing food
mandibulates – have appendages called mandibles that can be used to chew food
Chelicerates (group of arthropods)6 pairs of appendages; 1 pair are chelicerae
for feedingHorseshoe crabs
3 body regions cephalothorax – largest region with the most
obvious appendages abdomen – contains the gills telson – a long spike used for steering and defense
body is covered by a carapace—a hard outer covering
CheliceratesHorseshoe crabs (continued)
locomotion by walking or swimming by flexing the abdomen
mostly nocturnal scavengerssmaller males attach to females to mate, and
eggs are laid in a depression on the beach; larvae return to the sea to grow
Mandibulates (group of arthropod)Crustaceans—marine mandibulates Crustacean anatomy
3 main body regions: head thorax abdomen
appendages: 2 pairs of sensory antennae mandibles and maxillae used for feeding walking legs, swimmerets (swimming legs), legs
modified for reproduction, chelipeds (legs modified for defense)
Mandibulatesgas exchange
small crustaceans exchange gases through their body surface
larger crustaceans have gills
MoltingCrucial part of the life cycleFrequency of molting decreases with ageControlled by specific hormones produced in a
gland in the head, and initiated by environmental conditions
Decapods (group of mandibulate)Order decapoda; includes animals with 5
pairs of walking legs:crabslobsterstrue shrimp
1st pair of walking legs are chelipeds—pincers used for capturing prey and for defense
Wide range in size
DecapodsSpecialized behaviors
hermit crabs inhabit empty shellsdecorator crabs camouflage carapaces with
bits of sponge, anemones, etc.common blue crabs are agile swimmers
DecapodsNutrition and digestion
chelipeds are used for prey captureappendages are used for scavengingpredation and scavenging are usually
combined some decapods are deposit or filter feeders
DecapodsReproduction
sexes usually separatemales have appendages modified for clasping
females and delivering sperm spermatophores—sperm packages copulatory pleopods—2 pairs of anterior abdominal
appendages that deliver spermmost brood their eggs in chambers or modified
appendages
Cirripedia (class of arthropods)Class Cirripedia – the only sessile
crustaceansMost have calcium carbonate shellAttach directly to a hard surface, or have a
stalk for attachmentFilter feed using cirripeds—feathery
appendages which extend into the water when the shell is open
BarnaclesReproduction
hermaphroditiccross-fertilized using a long, extensible penisbrooded eggs hatch into nauplius larvaenauplius larvae develop into cyprid larvae,
which have compound eyes and a carapace of 2 shell plates
cyprid larvae attach using adhesive glands in antennae, then metamorphose into adults
Ecological Roles of ArthropodsArthropods as food
important food sources for marine animals and humans
copepods form a link between phytoplankton they eat and many animals that use them as a major food source
krill are consumed in large quantities by whales and other organisms
Ecological Roles of ArthropodsArthropods as symbionts
cleaning shrimps remove ectoparasites and other materials from reef fish
Some are ecotoparasites and endoparasitesbarnacles are commensal with many hosts
Ecological Roles of ArthropodsRole of arthropods in recycling and fouling
grass shrimp feed on detrital cellulose material, and so helps break down algae and grasses in tidal marsh ecosystems
barnacles are a serious fouling problem on ship bottoms attached barnacles can reduce ship speed by 30% special paints and other anti-fouling measures
Echinoderms: Animals with Spiny SkinsPhylum Echinodermata (sea stars, sea
urchins, sea cucumbers, brittle stars)Larval forms exhibit bilateral symmetry but
most adults exhibit a modified form of radial symmetry
Mostly benthic, and found at nearly all depths
Sea cucumbers and brittle stars are commonly found in deep-sea samples
Echinoderm StructureEndoskeleton—internal skeleton that lies just
beneath the epidermisSpines and tubercles project outward from
the ossiclespedicellariae—tiny, pincer-like structures
around the bases of spines that keep the body surface clean in some echinoderms
Echinoderm StructureWater vascular system—unique hydraulic
system that functions in locomotion, feeding, gas exchange and excretionwater enters by the madreporitepasses through a system of canalsattached to some canals are tube feet—hollow
structures with a sac-like ampulla within the body and a a sucker protruding from the ambulacral groove
Asteroidea (class of echinoderm)Class AsteroideaTypically composed of a central disk + 5
arms or raysOn underside, ambulacral grooves with tube
feet radiate from the mouth along each rayAboral surface—the side opposite the mouth,
which is frequently rough or spiny
AsteroideaFeeding in sea stars
most are carnivores or scavengers of invertebrates and sometimes fish
prey are located by sensing of substances they release into the water
sea stars envelope and open bivalves, evert a portion of the stomach, and insert it into the bivalves to digest them digestive glands located in each ray provide
digestive enzymes
AsteroideaReproduction and regeneration
sea stars can regenerate rays; some can regenerate themselves from a single ray plus part of the central disc
asexual reproduction involves division of the central disk and regeneration of each half into a new individual
most have separate sexes, which shed eggs and sperm into the water for fertilization and hatching into usually planktonic larvae
Ophiuroidea (class of echinoderm)Class Ophiuroidea
e.g. brittle, basket and serpent starsBenthic with 5 slender, distinct arms,
frequently covered with many spinesLack pedicellariae and have closed abulacral
groovesTube feet lack suckers and are used in
locomotion and feedingBrittle stars shed arms if disturbed
OphiuroidsFeeding in ophiuroids
carnivores, scavengers, deposit feeders, suspension feeders, or filter feeders
brittle stars usually filter feed by lifting their arms and waving them in the water
deposit feeders use their podia to gather organic particles from the bottom into food balls and pass them to the mouth
basket stars suspension feed by climbing onto corals/rocks and fanning their arms toward the prevailing current
OphiuroidsReproduction and regeneration in ophiuroids
autotomize—to cast off, as of an arm, when disturbed or seized by a predator
asexual reproduction by division into 2 halves and regeneration of individuals
mostly separate sexesmay shed eggs into water or brood them in
ovaries or a body cavityplanktonic larvae metamorphose into adults
within the water column
Echinoidea (class of echinoderm)Class Echinoidea – sea urchins and sand
dollarsBody enclosed by test—a hard exoskeletonBenthic on solid surfaces (sea urchins) or in
sand (heart urchins, sand dollars)Regular (radial) echinoids—sea urchins;
spheroid body with long, moveable spinesIrregular (bilateral) echinoids—heart
urchins and sand dollars; have short spines on their tests
EchinoideaFeeding in echinoids
feeding in regular echinoids mostly grazers which scrape algae and other food
materials from surfaces Aristotle’s lantern—a chewing structure of 5 teeth
feeding in irregular urchins irregular urchins are selective deposit feeders some sand dollars are suspension feeders
Holothuroidea (class of echinoderm)Class Holothuroidea- Sea CucumbersHave elongated bodies, and usually lie on 1
sideRespiratory trees—a system of tubules
located in the body cavity which accomplish gas exchange
Sexes are generally separateEggs may be brooded or incubated; larvae
are planktonic
HolothuroideaFeeding in sea cucumbers
mainly deposit or suspension feedersoral tentacles—modified tube feet coated with
mucus which are used to trap small food particles
Defensive behaviorCuvierian tubules—sticky tubules released
from the anus of some specieseviscerate—to release some internal organs
through the anus or mouth
Crinoidea (class of echinoderm)Class Crinoidea – sea lilies and feather starsPrimitive, flower-like echinodermsMost are feather stars, which seldom move
and cling to the bottom with grasping cirriSuspension feedersCan regenerate lost armsSeparate sexes shed eggs/sperm into the
water; larvae have fee-swimming stage, then attach to the bottom and metamorphose into minute adults
Ecological Roles of EchinodermsSpiny skins deter most predatorsPredators of molluscs, other echinoderms,
cnidarians, crustaceanscrown-of-thorns sea star eats coralsea urchins destroy kelp forests
Black sea urchins control algae growth on coral reefs
Sea cucumber poison, holothurin, has potential as a medicine