Invertebrate Biology

Phylogentic Relationships of Animals

Ancestral Protist

segmentation

true tissue

radial symmetry

bilateral symmetry

Deuterostomes:eucoelom

Protostome: schizocoelem

pseudocoelom

Porifera

Cnideria

Platyhelminthes

Nematoda

Mollusca

AnnelidaEchinodermata

ChordataArthropoda

no true tissues

acoelom

• Eukaryotic, multicellular organisms with cells organized into distinct tissues.

Heterotrophic nutrition

Most exhibit significant capacity for locomotion.

No cell walls; has a plasma membrane.

Includes sponges, sea anemones, snails, insects, sea stars, fish, reptiles, birds, and human beings.

Kingdom AnimaliaKingdom Animalia

Phylum Porifera

Class Desmospongiae

Class Calcarea

Class Hexactinellida

Class Sclerospongia

• No true tissues or organs• No symmetry• No nerves, muscles, mouth or

digestive system or • Sessile• Reproduce sexually and asexually• Skeletons composed of CaCO3 or

SiO2 spicules or spongin• Filter feeders

Phylum Porifera

5,000 species

Consists of organized cells supported by a skeleton of:

• spongin fibers• calcareous spicules• silica spicules• a combination of these, or perhaps no skeletal

structure at all

No GutSponges

Phylum PoriferaSponges

Phylum Porifera

• A few species of fish• seaslugs • hawks bill and loggerhead turtles

• Can use toxins to ward off predators

• Sponges provide habitat for wide variety of animals.

• As many as 16,000 different species of animals have been found in one loggerhead sponge.

• Most marine sponges (>80%)• All freshwater sponges• Leuconoid• Spongin and SiO2 spicules

• Contains all asconoid forms• Most syconoids• Generally small in stature• CaCO3 spicules

• Mostly deep sea forms • Glass-like lattice work• SiO2 spicules

• CaCO3 foundation with SiO2 spicules• Found in Pacific and West Indies

Asexual: • production of external buds that detach or remain to

form colonies • internal buds called gemmules that form during

unfavorable periods• fragmentation (regeneration)

Sexual (mostly hermaphroditic):• eggs are retained in the mesohyl and fertilized by

motile sperm that enter through the internal canals.  Zygotes develop into flagellated larvae,  which break loose and are carried away by water currents.

Phylum Cnidaria

Class Anthozoa

Class Hydrozoa

Class Scyphozoa

Class Cubozoa

CoralsAnemones

HydraPortuguese Man-Of-War

Stinging LimuFire Coral

True jellyfish Box jelliesSea wasps

Phylum Cnidaria

Stinging cells & 2 stages in life cycle

Radial symmetry

Tissues and organs

Diploblastic

Mouth and digestive cavity (blind sac gut)

9,000 species

Polyp Medusa

gastrovascular cavity

gastrovascular cavity

gastrodermis

mesoglea

epidermis

mouth/anus

mouth/anus

The Cnidarian Life Cycle

The Hydrozoan Life CycleThe Hydrozoan Life Cycle

Nematocysts

“Stinging Limu”

Class Hydrozoa

Hydrozoan Medusa

Close Up of a Portuguese Man-Of-War

Class Hydrozoa

Class Scyphozoa

Box Jellies

SeawaspClass Cubozoa

Subclass ZoanthariaOrder ActinariaSea Anemones

Class Anthozoa

Subclass HexacoralliaOrder Antipatheria

Black Coral & Wire Coral

Wire coral

Black coral

Class Anthozoa

“True” Stony Coralslobe

finger

mushroom

Porites rus

Class Anthozoa

Phylum Ctenophora

• Diploblastic• 8 rows or combs of cillia• Colloblasts- adhesive structures• Hydrostatic skeleton• Blind sack gut

Phylum Platyhelminthes

Class Turbellaria

Class Trematoda

Class Cestoda

Phylum Platyhelminthes

Flatworms

Blind digestive cavity

Bilaterally symmetrical

Thin, simple circulation

Sensory organs at front

Many parasitic

10,000 species

Fig. 33-10

Pharynx

Gastrovascularcavity

Mouth

Eyespots

Ganglia Ventral nerve cords

Class Turbellaria

Flatworm Anatomy

Pseudoceros dimidiatus

Pseudoceros cf. rubroanus

Pseudoceros ferrugineus

Pseudobiceros sp.

Planocera cf. oligoglena

Life History of a Blood FlukeClass Trematoda

Class Cestoda

• Bilaterally symmetrical and dorsoventrally flattened.• Body has more than two layers of cells with tissues and

organs. • Body has a through gut with a mouth and anus. • Body has no body cavity. • Has a blood system with blood vessels. • Has a well developed nervous system and a brain. • Has an eversible and retractable ectodermal proboscis.• Reproduction is by asexual fragmentation, or sexual,

when it is normally gonochoristic. • Most species are carnivorous and predatory. • Most are aquatic and marine, there are some terrestrial

and freshwater forms.

Phylum Nemertea

Phylum Nemertea

Ribbon worm

Phylum Rotifera• Bilaterally symmetrical. • Body has more than two cell layers, tissues and organs. • Body cavity is a pseudocoelom. • Body possesses a through gut with an anus. • Body covered in an external layer of chitin called a lorica.• Has a nervous system with a brain and paired nerves. • Has no circulatory or respiratory organs. • Reproduction mostly parthenogenetic, otherwise sexual

and gonochoristic. • Feed on bacteria, and protista, or are parasitic. • All live in aquatic environments either free swimming or

attached

Phylum Rotifera

Phylum NematodaRoundworms

Primitive body cavity

Gut & Anus

No circulatory system

Nervous system

Very successful- well adapted to every ecosystem

Many are parasites500,000? species

Phylum Nematoda

Phylum Mollusca

Class Polyplacophora

Class Gastropoda

Class Bivalvia

Class Cephalopoda

More than 500,000 known species

chitons Snailsnudibranchs

clams SquidOctopusCuttlefishNautilus

Phylum Mollusca

Well developed circulatory system

Nervous system with brain

Some with good eyes

Three main parts:

• Muscular foot- for movement• Visceral mass- contains most of the

internal organs

• Mantle cavity- houses gills

mantle

foot

visceral mass

• Grazers (radula- scraping tongue)

• Filter feeding

• Egg eaters

• Active predation

Class Polyplacophora

Spanish Dancer (nudibranch) & egg mass

Class GastropodaSubclass Opisthobranchia

Cone shell

Triton’s trumpet

Cowery Opihi

periwinkle

Class GastropodaSubclass Prosobranchia

Class Bivalvia

Class Cephalopoda

Day octopus

Class Cephalopoda

Class Cephalopoda

Class Cephalopoda

Octopus Intelligence

Mimic octopus from Indonesia

flatfish

lionfish

Sea snake

Blue-ringed octopus

Highly venomous

Phylum Annelida

Class Oligochaeta

Class Polychaeta

Class Hirudinia

earthworm leachesMarine worms

Phylum Annelida

Segmented worms, earthworms, leeches

Marine = polychaetes

True body cavity

Long tubular body

Muscles

9,000 species

Class Oligochaeta

Class Polychaeta

Class Hirudinia

• Segmentation (metameric body plan)• Eucoelomate• 15,000 species• Closed circulatory system, but no heart• Hydrostatic skeleton• Excretion- protonephridia, metanephridia, diffusion or gills• Simple gut• Respiration- diffusion or gills• Central nervous system- brain and nerve cord• Reproduction- asexual or sexual (many gonochoric)• Sensory system of tactile organs, taste buds, statocysts,

photoreceptor cells, and eyes with lenses.

FEEDING MODES- very diverse • Raptors• Herbivores• Browsers/grazers• Omnivores• Direct deposit feeders• Indirect deposit feeders• Suspension feeders

Phylum Arthropoda

Subphylum Trilobitomorpha

SubphylumCheliceriformes

Subphylum Uniramia

Subphylum Crustacea

trilobites spidersticksscorpions

insectscentipedesmillipedes

crabslobstersshrimpbarnacles

Phylogeny of Arthropods

Arthropoda

Worm-likeAncestor

Trilobites(extinct)

Annelids(worms)

Onychophorans(worms w/legs)

Chelicerates(spiders)

Crustaceans(lobsters)

Insects(butterflies)

Insects, crabs, spiders, barnacles

Most species; 80% are insects

Hard chitin exoskeleton (must shed to grow)

Circulatory system with blood, heart

10,000,000? species

Phylum Arthropoda

Subphylum Trilobitomorpha

Extinct Existed: 543-248 mya

Fig. 33-30

SubphylumCheliceriformes

SubphylumCheliceriformes

Sea spider

Subphylum Uniramia

Koa Bug

(a) Larva (caterpillar)(b) Pupa

(c) Later-stage pupa (d) Emerging

adult

(e) Adult

Metamorphosis of a Butterfly

Banded coral shrimp

Spiny lobster Hawaiian cleaner shrimpYellow spotted guard crab

Anemone carrying hermit crab

Subphylum Crustacea

Phylum Echinodermata

Class Astroidae

Class Ophiuroidae

Class Echinoidae

Class Holothuroidae

Class Crinoidae

Sea stars Brittle stars

Crinoids

Sea urchins Sea cucumbers

Phylum Echinodermata

No circulatory system

No respiratory system

Excretion (N elimination) by diffusion

Simple nervous system, no brain

Water-vascular system

Sea Star Anatomy

Phylum Echinodermata

Tube feet & associated plumbing

Used for walking, clinging to substrate & holding food

Water Vascular System

Linckia sp.

Acanthaster planci

Class Astroidae

Class Ophiuroidae

Class Crinoidae

Echinometra mathaei

Colobocentrotus atratus

Echinothrix calamaris

Slate pencil urchin

Collector urchin

Class Echinoidae

Holothuria atra

Polyplectana kerfersteninii

Class Holothuroidae