marine midterm 2

Phylum Mollusca

• Soft-bodied coelomates

• Bilateral symmetry

• Protostomes (Lophotrochozoa)

• Three body regions:

  • Head

  • Visceral mass

  • Muscular foot

• Key words: mantle, foot, visceral mass, radula

Class Caudofoveata

• Worm-like

• No shell

• No true foot

• Covered with calcareous spicules

• Burrow in soft sediment

• Feed on microorganisms

Remember:
Looks like a tiny armored worm.

Class solenogastres

• Worm-like

• No shell

• Tiny foot groove

• Covered with spicules

• Feed on cnidarians

• Mostly deep sea

Difference from Caudofoveata:
Has a reduced ventral foot.

Class monoplacophora

• Single cap-shaped shell

• Deep ocean

• Repeated organs (serial repetition)

• Primitive molluscs

Remember:
Single shell + repeated gills.

Class monoplacophora

• Single cap-shaped shell

• Deep ocean

• Repeated organs (serial repetition)

• Primitive molluscs

Remember:
Single shell + repeated gills.

Class gastropoda

Largest mollusc class

Characteristics:

• One shell (usually)

• Torsion during development

• Well-developed head

• Radula

• Muscular crawling foot

Examples

• Snails

• Slugs

• Limpets

• Nudibranchs

Most diverse mollusc.

Subclass prosobranchia

• Marine snails

• Operculum present

• Gills in front of heart

• External shell

Examples:
Periwinkles
Whelks

Subclass opisthobranchia

• Sea slugs

• Nudibranchs

• Shell reduced or absent

• Bright coloration

• Many use cnidarian nematocysts

Marine only.

Subclass Pulmonata

• Air-breathing snails

• Mantle cavity becomes lung

• Mostly terrestrial

• Some freshwater

Examples:
Garden snail

Class bivalvia

Two hinged snail

Characteristics:

• No head

• No radula

• Filter feeders

• Large gills

• Muscular foot for burrowing

Examples:
Clams
Mussels
Scallops
Oysters

Class scaphopoda

“Tusk shells”

Characteristics:

• Tubular shell

• Burrow in sediment

• Feed using captacula

• Marine

Unique:
Open shell at both ends.

Class cephalopoda

• Tentacles

• Large brain

• Camera eyes

• Closed circulation

• Powerful beak

• Radula

• Jet propulsion

Examples:
Octopus
Squid
Cuttlefish
Nautilus

Phylum Nemertea

• Ribbon worms

• Unsegmented

• Complete digestive tract

• Closed circulatory system

• Rhynchocoel

• Eversible proboscis

• Marine predators

Key word:
Rhynchocoel

Phylum Annelida

Segmented worms

Characteristics:

• Segmentation

• True coelom

• Chaetae

• Closed circulation

• Complete gut

• Metanephridia

Polycheates

Marine annelids

Characteristics:

• Parapodia

• Many chaetae

• Separate sexes

• Trochophore larvae

Errantia

• Active predators

• Large parapodia

• Well-developed head

• Large jaws

Examples:
Nereis

Sedentaria

• Tube dwellers

• Deposit feeders

• Reduced parapodia

• Often have feeding tentacles

Examples:
Feather duster worms

Clade Clitellata

Characteristics:

• Clitellum

• Hermaphrodites

• No parapodia

• Direct development

Oligochaetes

Examples:
Earthworms

Characteristics:

• Few chaetae

• Burrowers

• Important decomposers

Clade Lophophorata

horseshoe-shaped lophophore

• Tube dwelling

• Suspension feeder

• U-shaped gut

Phylum Bryozoa

• Colonial

• Zooids

• Lophophore

• Calcium carbonate skeleton

Phylum. Brachiopoda

• Two shells

• Dorsal and ventral valves

• Lophophore

• Pedicle attachment

Not the same as bivalve

Phylum Arthropoda

Largest animal phylum

Characteristics:

• Segmented body

• Jointed appendages

• Chitin exoskeleton

• Molting (ecdysis)

• Open circulation

• Ventral nerve cord

Examples:
Crabs
Shrimp
Barnacles
Insects
Spiders

Class Hirudinea

• Segmented annelids

• No chaetae (bristles)

• Anterior and posterior suckers

Anatomy:

• Flattened body

• Fixed number of segments

• Coelom reduced

Phylum phoronida

• Tube-dwelling marine worms

• Horseshoe-shaped lophophore

Anatomy:

• U-shaped digestive tract

• Complete gut

• Chitinous tube

“Phoronids = lophophore in a tube.”

Clade Rouphozoa

• Platyhelminthes

• Gastrotricha

• Small, soft-bodied animals

• Bilateral symmetry

• Mostly ciliated

• No molting

Phylum Platyhelminthes

• Dorsoventrally flattened

• Acoelomate

• Bilateral symmetry

• No circulatory system

• No respiratory system

• Incomplete gut (most)

• “Flat body = Flatworm.”

Turbellarians

• Free-living flatworms

• Ciliated epidermis

• Eyespots

• Auricles

• Strong regeneration

Feeding:

• Predators and scavengers

Order polycladida

• Marine flatworms

• Highly branched intestine

Features:

• Bright colors

• Leaf-like body

• Numerous eyes

• “Poly = many branches.

Order tricladida

• Three-branched intestine

• Eyespots

• Excellent regeneration

• “Tri = three gut branches.”

Class Rhabdocoela

• Simple sac-like intestine

• Small

• Free-living

• Mostly aquatic

Class Acentrosomata

• Small free-living flatworms

• Lack centrosomes in cells

• Marine

• Primitive flatworms

Infraclass Neodermata

Includes:

• Trematoda

• Monogenea

• Cestoda

• All parasitic

• Syncytial tegument

• Complex life cycles

• “Neo = new skin (tegument).”

Cohort trematoda

• Leaf-shaped parasites

• Oral sucker

• Ventral sucker

• Complex life cycle

• Usually snail intermediate host

• “Flukes = suckers.”

Cohort Mongoenea

• External fish parasites

• Single-host life cycle

• Posterior hooks (opisthaptor)

• “Mono = one host.”

Cohort Cestoda

Tapeworms

• No digestive tract

• Scolex

• Proglottids

• Absorb nutrients through body wall

Phylum Gastrotricha

• Tiny aquatic animals

• Ventral cilia

• Adhesive tubes

• Complete gut

Clade Ecdysozoa

• Molting cuticle (ecdysis)

• Growth by shedding exoskeleton

Phylum Kinorhyncha

Common name:
Mud dragons

• Segmented body

• Scalids

• Molt

• Marin

Phylum priapulida

Penis worm

• Retractable introvert

• Scalids

• Predator

Phylum Loricifera

• Tiny marine animals

• Lorica (protective shell)

• Scalids

• Molt

Phylum Nematoda

Round worms

• Cylindrical body

• Pseudocoelom

• Complete digestive tract

• Molt

• Thick cuticle

Phylum Nematomorpha

Horsehair worms

• Very long and thin

• Juveniles parasitic

• Adults free-living

Clade panarthropoda

• Segmented body

• Paired appendages

• Molting cuticle

• Includes:

  • Tardigrada

  • Onychophora

  • Arthropoda

Phylum Tardigrada

Water bears

• Eight legs

• Claws

• Molt

• Cryptobiosis (tun state)

Phylum onychophora

Velvet worms

• Soft body

• Lobopod legs

• Slime glands for prey capture

• Tracheae