INVERTEBRATES Mollusca, Annelida, Arthropoda, Echinodermata Animals that lack vertebrae (classed by a characteristic they don’t have.) 97% of all species.

INVERTEBRATESINVERTEBRATES

Mollusca, Annelida, Arthropoda, Mollusca, Annelida, Arthropoda, EchinodermataEchinodermata

Animals that lack vertebrae (classed by a characteristic they don’t have.) 97% of all species on Earth are invertebrates.

Phylum MolluscaPhylum Mollusca

• More species (200,000+) than any other More species (200,000+) than any other animal phylum except Arthropodaanimal phylum except Arthropoda

• Soft body – often protected by CaCO3 shell

• Unsegmented, typically bilaterally symmetrical

Phylum MolluscaPhylum Mollusca

©2004 Amanda Demopoulos

Mollusca: Major Characteristics

1.Cephalization have a distinct head with sense organs & brain (mostly)

2.Bilaterally symmetrical (mostly)

                                   SNAIL, CLAM, CHITON, & SQUID

Basic Mollusk Body Plan

Head (eyes/sensory), visceral mass (organs), muscular footMantle – covers visceral mass, secretes shellRadula – Ribbon of small chitin teeth used in feedingGills (ctenidia-comb like) for gas exchange in mantle cavity

Radula – Ribbon of small chitin teeth used in feeding

4 Classes of Mollusca1.1.Class PolyplacophoraClass Polyplacophora Many-plate-bearing = Many-plate-bearing =

Chitons 800 speciesChitons 800 species

• Mostly graze algae on rocky shorelinesMostly graze algae on rocky shorelines

• Exclusively marineExclusively marine

• 8 overlapping plates8 overlapping plates

2. Gastropoda 2. Gastropoda snails, slugs, nudibranchs, snails, slugs, nudibranchs,

conchs & abaloneconchs & abalone

Most gastropods are herbivores

Class GastropodaClass Gastropoda

Stomach-Foot (class Gastropoda) contains about 70% of all mollusk species. A few stomach-foots are found on land. The stomach-foot include: snails, limpets and abalones, which have shells.

Slugs and nudibranchs are also stomach-foots, but do not have shells.

Stomach-Foot

AbalonesAbalones

SnailsSnails

SnailsSnails

SnailsSnails

NudibranchsNudibranchs

3. Pelecypoda or Bivalvia 3. Pelecypoda or Bivalvia clams, oysters, & musselsclams, oysters, & mussels

No head and no radula

Most bivalves are suspension feeders

Class BivalviaClass Bivalvia

Biv

alv

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Biv

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Hinged, 2-valved shellHinged, 2-valved shell (oysters, clams, mussels, (oysters, clams, mussels, scallops) muscles keep closed

No head , no radula Sedentary lifestyleSedentary lifestyle Some have muscular foot for Some have muscular foot for burrowing (clams)burrowing (clams) Gills used for suspension used for suspension feeding & respirationfeeding & respiration

Water enters and leaves Water enters and leaves through siphonsthrough siphons

Some anchor to substrate Some anchor to substrate (mussels)(mussels) Scallops – Swim! (repeated Scallops – Swim! (repeated clapping of valves)clapping of valves)

Class BivalviaClass Bivalvia

4. Cephalopoda 4. Cephalopoda squid, octopus, & nautilus squid, octopus, & nautilus

Class CephalopodaClass Cephalopoda- Octopus and squid have beak-like jaws- Octopus and squid have beak-like jaws

- Mouth is central among tentacles- Mouth is central among tentacles

Octopus8 arms, non-retractable w/ 2 rows of suckers

Nautilus60-90 suckerless tentacles

Squid8 arms + 2 tentacles non-

retractable w/suckers and hooks

Cuttlefish8 arms + 2 tentacles,

retractable w/ suckers, no hooks

CephalopodsCephalopods

(a)

(b)(c)

Note the different shells in cephalopods - external in Nautilus, internal in squids, and missing in octopuses.

Octopuses are considered among the most intelligent invertebrates.

Chambered nautiluses are the only living cephalopods with an external shell.

Squids are speedy carnivores with beaklike jaws and well-developed eyes.

PHYLUM AnnelidaPHYLUM Annelida

EarthwormsEarthwormsLeechesLeechesTubewormsTubeworms

Annelids: Major Characteristics

1. Cephalization

2. Bilateral symmetry3. Coelom well developed and divided by septa (except in leeches); coelomic fluid supplies turgidity and acts as a hydrostatic skeleton

SegmentedSegmented worms worms (1mm-3m)(1mm-3m)•Body composed of Body composed of repeated segmentsrepeated segments

Annelids: Major Characteristics•Body wall

•Outer circular and inner longitudinal muscle layers

•Protective elastic outer transparent moist cuticle secreted by epithelium

•Closed circulatory system

•Respiratory gas exchange through skin, gills or parapodia

•Digestive system of many has 2 openings, Digestive system of many has 2 openings, mouth and anus (some have no gut)mouth and anus (some have no gut)

•Excretory system

•Nervous systems

1. Polychaeta Tubeworms, feather dusters, bristle worms, mainly marine•Free-living predatorsFree-living predators•BurrowingBurrowing•Tube buildingTube building

Three Classes

Body segments have Body segments have pairs of parapodiapairs of parapodia

• locomotionlocomotion

• feeding feeding

• gas exchangegas exchange

• protection protection

• tipped with tipped with setaesetae (bristles), (bristles), often 4 pairsoften 4 pairs

2. Oligochaeta• Earthworms, mainly Earthworms, mainly terrestrial and terrestrial and freshwater freshwater • Few marine speciesFew marine species• Benthic – mud and Benthic – mud and sand (deposit feeders)sand (deposit feeders)• No parapodiaNo parapodia• Locomotion – Locomotion – expansion and expansion and contractioncontraction

Three Classes

Eart

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Eart

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Annelid MovementAnnelid Movement

3. Hirudinea•Leeches•HirudinHirudin – anticoagulating – anticoagulating chemical so blood does not chemical so blood does not clotclot•mainly freshwater but with marine and terrestrial species•No parapodiaNo parapodia

•One anterior/one One anterior/one posterior suckerposterior sucker

Three Classes

Phylum ArthropodaPhylum Arthropoda

The vast majority of known animal

species, including insects, crustaceans, and

arachnids, are arthropods. All

arthropods have segmented

exoskeleton and jointed

appendages.

•Most species of any phylum – over 1 Most species of any phylum – over 1 million - 75% of all animals species million - 75% of all animals species describeddescribed

•Insects, spiders, centipedes, crabs, Insects, spiders, centipedes, crabs, lobsters, shrimp, barnacles, etc.lobsters, shrimp, barnacles, etc.

•Segmented, bilaterally symmetrical Segmented, bilaterally symmetrical bodybody•Jointed appendagesJointed appendages•ExoskeletonExoskeleton made of chitin made of chitin•Growth requires Growth requires moltingmolting - - defenselessdefenseless

•Body segmentsBody segments•Head, thorax, abdomenHead, thorax, abdomen

•Some groups have head and Some groups have head and thorax fused = cephalothoraxthorax fused = cephalothorax

•Discuss 3 subphyla and Discuss 3 subphyla and representative classesrepresentative classes

Phylum ArthropodaPhylum Arthropoda

A.A. Class MerostomataClass Merostomata (=legs attached to mouth)(=legs attached to mouth)

• Horseshoe crabs-Not true crabsHorseshoe crabs-Not true crabs• Named for feeding appendages – Named for feeding appendages –

cheliceraechelicerae• Distinctive, horseshoe-shaped carapaceDistinctive, horseshoe-shaped carapace• No antennaeNo antennae• Benthic predators/scavengers on clams Benthic predators/scavengers on clams

and small invertebratesand small invertebrates• No jaws - Grind food with bristles on No jaws - Grind food with bristles on

walking legs (must be walking to “chew”)walking legs (must be walking to “chew”)• Much of what we know understand about Much of what we know understand about

vision based on horseshoe crab eyesvision based on horseshoe crab eyes• Blood is used to test injectable Blood is used to test injectable

pharmaceutical solutions for bacterial pharmaceutical solutions for bacterial contamination contamination

1. Subphylum Chelicerata1. Subphylum Chelicerata

B. B. Class PycnogonidaClass Pycnogonida (= thick (= thick knees, Sea spiders)knees, Sea spiders)

• All marineAll marine• Superficially resemble Superficially resemble

spidersspiders• Mouth at end of large Mouth at end of large

proboscisproboscis• CarnivoresCarnivores

•Feed on sea anemones, Feed on sea anemones, hydrozoans, hydrozoans,

•other soft invertsother soft inverts• Legs much longer than body, Legs much longer than body,

more than 8more than 8

2. Subphylum Chelicerata2. Subphylum Chelicerata

C. C. ArachnidaArachnida spiders, spiders, scorpions, mitesscorpions, mites

• Largest class in Largest class in ChelicerataChelicerata

• Cephalothorax and Cephalothorax and abdomenabdomen

• Mouth called chelicerae Mouth called chelicerae (first appendage(first appendage•Pinchers or fangsPinchers or fangs

• PedipalpsPedipalps•Second pair of appendagesSecond pair of appendages•Handle prey, sensoryHandle prey, sensory

• Four pair of walking legsFour pair of walking legs

2. Subphylum Chelicerata2. Subphylum Chelicerata

2. Subphylum Chelicerata2. Subphylum Chelicerata ArachnidsArachnids

PHOTO: Bill Rudman

Chelicerae are feeding appendages

Cheliceriform AnatomyCheliceriform Anatomy

Class TrilobitaClass Trilobita

•MarineMarine

•ExtinctExtinct since 250 since 250 myamya

•Rich fossil history Rich fossil history because of because of exoskeletonexoskeleton

•Dorso-ventrally Dorso-ventrally flattenedflattened

• Contains majority of marine arthropod speciesContains majority of marine arthropod species• Gills + two pairs of antennae (sensory)Gills + two pairs of antennae (sensory)• Larval forms – nauplius and zoeaLarval forms – nauplius and zoea

A. A. Class CopepodaClass Copepoda (=oar foot, Copepods) (=oar foot, Copepods)• Extremely abundant holoplankton (always plankton)Extremely abundant holoplankton (always plankton)• Some live on/in substrates (benthos)Some live on/in substrates (benthos)• **Among most abundant animals on earth****Among most abundant animals on earth**• Important primary consumers of phytoplanktonImportant primary consumers of phytoplankton• Small << 1-2 mmSmall << 1-2 mm• Some parasitic formsSome parasitic forms

3. Subphylum Crustacea3. Subphylum Crustacea (40K species) (40K species)

B. B. Class CirripediaClass Cirripedia (= hairy foot, (= hairy foot, Barnacles)Barnacles)•Active suspension feeders (filter Active suspension feeders (filter feeders)feeders)•Use feathery Use feathery cirricirri (modified (modified swimming appendages)swimming appendages)

•Sessile (attached to surfaces-Sessile (attached to surfaces-whales, piers)whales, piers)

•Fouling organisms (boats, whales)Fouling organisms (boats, whales)•Resemble mollusks superficially – Resemble mollusks superficially – calcareous platescalcareous plates

3. Subphylum Crustacea3. Subphylum Crustacea

C. C. Class MalacostracaClass Malacostraca (=soft (=soft shell, 75% crustacean species-shell, 75% crustacean species-Discuss 4 Orders)Discuss 4 Orders)

1. 1. Order AmphipodaOrder Amphipoda (Amphipods) beach hoppers, (Amphipods) beach hoppers, sand fleas, whale licesand fleas, whale lice

• Laterally compressedLaterally compressed

•Generally small (< 2 cm), Generally small (< 2 cm), but larger in deep oceanbut larger in deep ocean

•Head and tail downwardHead and tail downward

• Widespread distributionWidespread distribution

•Generally free livingGenerally free living

•Important scavengersImportant scavengers

3. Subphylum Crustacea3. Subphylum Crustacea

C. C. Class MalacostracaClass Malacostraca2. 2. Order IsopodaOrder Isopoda (Isopods-rock (Isopods-rock

lice, fish lice)lice, fish lice)• Dorsoventrally Dorsoventrally

compressedcompressed• Generally small (< 2 cm), but Generally small (< 2 cm), but

larger in deep oceanlarger in deep ocean

• Related to terrestrial pill Related to terrestrial pill bugsbugs

• Widespread distributionWidespread distribution• Generally free livingGenerally free living

• Important scavengersImportant scavengers

• Some parasitesSome parasites

3. Subphylum Crustacea3. Subphylum Crustacea

C. C. Class MalacostracaClass Malacostraca

3. 3. Order EuphausiaceaOrder Euphausiacea (Krill) - (Krill) - holoplanktonholoplankton

•Laterally compressedLaterally compressed•Up to 10 cm long (usually smaller)Up to 10 cm long (usually smaller)

•Head and anterior segments fused to form Head and anterior segments fused to form distinct distinct carapacecarapace

•Widespread distributionWidespread distribution

•Important primary consumers and Important primary consumers and predatorspredators

•Important prey for larger consumers Important prey for larger consumers (whales, penguins, fish)(whales, penguins, fish)

•Keystone speciesKeystone species in some ecosystems in some ecosystems (Polar, Southern Ocean)(Polar, Southern Ocean)

•Aggregate in schools (billions of individuals)Aggregate in schools (billions of individuals)

3. Subphylum Crustacea3. Subphylum Crustacea

C. Class Malacostraca4. Order Decapoda (=10 legs, Crabs,

Lobsters, Shrimps)• Most species in Crustacea

(~10,000)

• Scavengers/Predators/Both• Largest crustaceans• Five pairs of walking legs

(deca=10)

• First pair usually modified as claws for feeding/defense

• Well-developed carapace = cephalothorax

• Rest of body = abdomen, tail

• Laterally compressed, except crabs – abdomen under cephalothorax

3. Subphylum Crustacea3. Subphylum Crustacea

Fig. 7.30

4. Subphylum-4. Subphylum-UniramiaUniramia

A.A. Class Insecta Class Insecta = Hexapoda (6 = Hexapoda (6 footed)footed)

•1 million species described to 1 million species described to datedate

•Found in every known Found in every known terrestrial + freshwater terrestrial + freshwater habitat, some marine except habitat, some marine except deep seadeep sea

•Diversity attributable to Diversity attributable to • Feeding specializationFeeding specialization• Dispersal capabilitiesDispersal capabilities• Predator-avoidance Predator-avoidance

possibilities (flight)possibilities (flight)

Tracheal tubes are used in gas exchange

“Insects are more species rich than all other forms of life

combined.”

Insect wings are modified cuticle, not

appendages

4. Subphylum-4. Subphylum-UniramiaUniramiaA.A. Class Insecta Class Insecta = Hexapoda (6 footed) = Hexapoda (6 footed)

Insect AnatomyInsect Anatomy

In incomplete metamorphosis (not shown), the juvenile looks like the adult

Complete MetamorphosisComplete Metamorphosis

4. Subphylum-4. Subphylum-UniramiaUniramia

A.A. Class DiplopodaClass Diplopoda = 2 pair of legs per segment = = 2 pair of legs per segment = millipedesmillipedes

B.B. Class ChilopodaClass Chilopoda = 1 pair of legs per segment = = 1 pair of legs per segment = centipedescentipedes Millipedes, herbivores,

were perhaps the first land animals

Centipedes are carnivores

Echinoderms, such as sand dollars, sea

stars, and sea urchins, are aquatic animals that display radial symmetry as adults. They move

and feed by using a network of internal cannals to pump water to different pars of the body.

Phylum EchinodermataPhylum Echinodermata

“ “Spiny skin” 6000 speciesSpiny skin” 6000 speciesSea lilies, feather stars, Sea lilies, feather stars, brittle stars, sea stars, sand brittle stars, sea stars, sand dollars, sea urchins, sea dollars, sea urchins, sea biscuits, sea cucumbersbiscuits, sea cucumbersRadial symmetryRadial symmetryEndoskeleton = hard plates, Endoskeleton = hard plates, ~95% calcium carbonate, ~95% calcium carbonate, covered by skincovered by skinComplete digestive, nervous Complete digestive, nervous systems, and reproductive systems, and reproductive organsorgansRegenerationRegenerationWater vascular system = Water vascular system = internal hydraulic systeminternal hydraulic system

Phylum EchinodermataPhylum Echinodermata

Sea stars posses

multiple arms, upon which are numerous tube

feet, and a calciferous

endoskeleton

Sea StarsSea Stars

Tube feetTube feet (podia) (podia) extended by pressure extended by pressure from from ampullae ampullae (muscular sacs)(muscular sacs)Tube feet used for Tube feet used for locomotion, feeding, locomotion, feeding, sensory functionssensory functions

Phylum EchinodermataPhylum Echinodermata

Phylum EchinodermataPhylum Echinodermata

Crown of ThornsAcanthaster planci

Echinoderm AnatomyEchinoderm Anatomy

The EndThe End