Marine Mollusks

Marine MOLLUSCS Robert Perry Malibu High School

rev 2012

Question: Where do mollusks “fit� in the evolution of animals on earth?

eukaryotes

ANIMALS

THE ANIMAL KINGDOM

NO TISSUES NO SYMMETRY

porifera

NO ORGANS RADIAL SYMMETRY ORGANS

cnidaria

BILATERAL SYMMETRY

platyhelminthes

bryozoa arthropoda mollusca

annelida echinodermata

cho r

dat a Animal cladogram based on DNA sequencing From National Museum of Natural History

MOLLUSKS:

--COELOMATE

(what is a coelom?)

--CALCAREOUS SHELL (not all mollusks have one)

--85,000+ SPECIES --SW, FW, DAMP TERRESTRIAL

--MOST ABUNDANT INVERT ANIMALS IN OCEAN

Phylum Mollusca Mollusks have a soft, muscular body which may or may not be protected by one or more shells. The 3 body regions are: 1--Headfoot.

2--Visceral Mass.

3--Mantle Cavity.

mollusca “mollis� = soft

(under shell)

visceral mass (under shell)

mantle cavity (Pallium)

Mantle layer: secretes the shell.

Cavity contains: ctenidia and openings from digestive and reproductive systems.

Brown turban, or kelp snail Norrisia norrisii

Vital organs such as: heart gonads osphradia (some) kidneys digestive system

headfoot Sensory information Feeding Locomotion

The 5 Classes of Mollusks P h y lu m M OLLUSCA C la s s G ASTROPODA

Snails, slugs.

C la s s B IV A L V IA

Clams, oysters, scallops, mussels.

C la s s A M P H IN E U R A (P o ly p la c o p h o r a )

Chitons.

C la s s CEPHALOPODA

Octopus, squid.

C la s s SCAPHOPODA

Tusk or tooth shells.

Last 3 images from internet authors unknown

What’s a GASTROPOD?

Pink abalone Haliotis corrugata

mantle/cavity shell epipodium labial palps

mouth & radula foot

ABALONE GAS EXCHANGE

ABALONE REPRODUCTION

COMMON GASTROPODS AROUND HERE

California Cone Conus californicus

COMMON GASTROPODS AROUND HERE

California Cone Conus californicus

COMMON GASTROPODS AROUND HERE

Chestnut Cowry Cypraea spaedicea

COMMON GASTROPODS AROUND HERE

Kellet’s Whelk Kelletia kelletii

COMMON GASTROPODS AROUND HERE

Giant Keyhole Limpet Megathura crenulata

COMMON GASTROPODS AROUND HERE

Brown turban, or kelp snail Norrisia norrisii

COMMON GASTROPODS AROUND HERE

“Worm” Snail Serpulorbis squamigerus

COMMON GASTROPODS AROUND HERE

“Worm” Snail Serpulorbis squamigerus

COMMON GASTROPODS AROUND HERE

“Worm” Snail Serpulorbis squamigerus

COMMON GASTROPODS AROUND HERE

“Worm” Snail Serpulorbis squamigerus

COMMON GASTROPODS AROUND HERE

“Worm” Snail Serpulorbis squamigerus

COMMON GASTROPODS AROUND HERE

“Worm” Snail Serpulorbis squamigerus

GASTROPODS NOT SO COMMON AROUND HERE ANYMORE

Red Abalone Haliotis rufescens

GASTROPODS NOT SO COMMON AROUND HERE ANYMORE

Black Abalone Haliotis cracherodii Malibu Malibu, 1972

GASTROPODS NOT SO COMMON AROUND HERE ANYMORE

Black Abalone Haliotis cracherodii Channel Islands

San Nicolas Island early 1960’s

GASTROPODS NOT SO COMMON AROUND HERE ANYMORE

Pink Abalone Haliotis corrugata

Green Abalone pearl Haliotis fulgens

GASTROPOD MOLLUSKS:

MANTLE VISCERAL MASS

HEADFOOT

TORSION: HOW GASTROPODS “GOT THEIR TWIST” (OR SPIRAL SHAPE). (dorsal view)

ANCIENT

GASTROPOD

(lateral view)

TORSION: WHAT CHANGES OCCURRED AS GASTROPODS EVOLVED ? WHY?

MODERN

GASTROPOD

MANTLE CAVITY AND CTENIDIA:

SUBCL:OPISTHOBRANCHIA SUBCL:PROSOBRANCHIA

SUBCL:PULMONATA

THREE LAYERS OF A MOLLUSK SHELL: PERIOSTRACUM PRISMATIC LAYER

NACREOUS LAYER

MANTLE SIPHON ANTENNA + EYE

MOUTH

FOOT

MOUTH

EYE SHELL ANTENNA

SIPHON

MANTLE

OPISTHOBRACHS GASTROPODS WITHOUT EXTERNAL SHELLS

Janolus Nudibranch Janolus barbarensis

OPISTHOBRANCHS: THREE COMMON SUBORDERS APLYSIOMORPHA

Internal shell

“sea hares”

AEOLIDACEA

Gills exposed along back

Eolid Nudibranchs

DORIDACEA Dorid Nudibranchs

“nudibranch” means naked gills Gills in circle around anus

rhinophores cerata oral tentacles

headfoot

Spanish Shawl Nudibranch Flabellina iodinea

NUDIBRANCH ANATOMY tail

OPISTHOBRANCH FOOD & FEEDING:

http://www.asnailsodyssey.com/LEARNABOUT/NUDIBRANCH/nudiFood.php

Common Opisthobranchs around here.

Hares and Nudibranchs

Sea Hare Aplysia californica

http://www.asnailsodyssey.com/LEARNABOUT/NUDIBRANCH/nudiFood.php

Common Opisthobranchs around here.

Hares and Nudibranchs

Sea Hare Aplysia californica

Common Opisthobranchs around here.

Hares and Nudibranchs

Sea Hare Aplysia californica

Common Opisthobranchs around here.

Hares and Nudibranchs

Sea Hare Aplysia californica

Common Opisthobranchs around here.

Hares and Nudibranchs

Sea Hare Aplysia californica

Common Opisthobranchs around here.

Hares and Nudibranchs

Striped Hare Navanax inermis

Common Opisthobranchs around here.

Hares and Nudibranchs

Striped Hare Navanax inermis

Striped Hare Navanax inermis

Common Opisthobranchs around here.

Hares and Nudibranchs

MacFarland’s Dorid Chromadoris macfarlandi

Common Opisthobranchs around here.

Hares and Nudibranchs

Black and white spotted Triopha Triopha maculata

Common Opisthobranchs around here.

Hares and Nudibranchs

Shaggy Rug Nudibranch Aeolidia papillosa

Common Opisthobranchs around here.

Hares and Nudibranchs

Shaggy Rug Nudibranch Aeolidia papillosa

Common Opisthobranchs around here.

Hares and Nudibranchs

Spanish Shawl Nudibranch Flabellina iodinea

Common Opisthobranchs around here.

Hares and Nudibranchs

Cerata with nematocysts

Opalescent Nudibranch Hermissenda crassicornis

Common Opisthobranchs around here.

Hares and Nudibranchs

Catalina Triopha Triopha catalinae

What’s a BIVALVE ?

COMMON BIVALVES AROUND HERE...

Giant Rock Scallop Crassidoma gigantea

COMMON BIVALVES AROUND HERE...

Giant Rock Scallop Crassidoma gigantea

COMMON BIVALVES AROUND HERE...

Giant Rock Scallop Crassidoma gigantea

COMMON BIVALVES AROUND HERE...

California Mussel Mytilus californianus

ANTERIOR REGION

POSTERIOR REGION

DORSAL REGION

VENTRAL REGION SHELL ORIENTATION QUESTION: WHICH OF THE 2 SHELLS IS THIS? HOW TO YOU KNOW?

BIVALVE SHELL FEATURES AND ORIENTATION

DORSAL HINGE LIGAMENT

ANTERIOR ADDUCTOR MUSCLE

POSTERIOR ADDUCTOR MUSCLE

HOW DO THE SHELLS OPEN? HOW DO THEY CLOSE?

SHELL ANATOMY OF Mytilus californianus

INTERNAL ANATOMY OF Mytilus californianus

DORSAL

POSTERIOR

ANTERIOR VENTRAL (gonads removed)

Mytilus FEEDING AND GAS EXCHANGE

n

n

SIPHONS

FOOT

HOW DO CLAMS MOVE? HOW DO THEY CARRY OUT LIFE FUNCTIONS?

CTENIDIA WHAT 2 MAIN LIFE FUNCTIONS ARE PERFORMED BY THE BIVALVE CTENIDIA?

Rock-Boring Clam (Piddock) Penitella penita

What does the word “veliger” mean?

CEPHALOPODA

Cephalopoda (Greek plural Κεφαλόποδα (kephalópoda); "head-foot"): These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot.

COMMON CEPHALOPODS AROUND HERE

Two spot Octopus Octopus bimaculatus

Octopus feeding:

COMMON CEPHALOPODS AROUND HERE

Two spot Octopus Octopus bimaculatus

Copy this link into browser:

http://www.wimp.com/octopusmimic/ Thanks, Mark

Octopus mating:

COMMON CEPHALOPODS AROUND HERE

Two spot Octopus Octopus bimaculatus

COMMON CEPHALOPODS AROUND HERE

© Robert Perry

Common Market Squid Loligo opalescens

EXTINCT

WHAT ARE THE 5 LIVING FORMS OF CEPHALOPODS?

External anatomy

Identification of foods eaten by squids is made difficult by the often fragmented and well-digested state of the stomach contents.

Researchers in the Moss Landing Marine Laboratories, California therefore rely mostly on the presence of paired eye-lenses, mandibles, statoliths, otoliths, polychaete jaws, and so on, to identify prey items in the stomach contests of Dorytheuthis opalescens captured by trawling in Monterey Bay, California. To estimate prey preferences, the researchers compare frequencies of occurrence of prey in the diet with those in the habitat. Results show that crustaceans predominate in the diets of both small and large squids, with euphausiids being the most preferred. A few fishes and gastropods are also eaten.

Internal anatomy

Loligo opalescens Common or Market Squid Common Market Squid Loligo opalescens

Loligo opalescens egg capsules

Common Market Squid Loligo opalescens

Loligo opalescens paralarvae

What methods are used to catch Loligo ?

Common Market Squid Loligo opalescens

Common Market Squid Loligo opalescens

Common Market Squid Loligo opalescens

Common Market Squid Loligo opalescens

The End