http://www.youtube.com/watch?v=Gg57Id z7Bs4 http://www.youtube.com/watch?v=vP_td9 q_344

General Name means soft body this is one of the largest animal phyla, besides Arthropoda There are nearly 75,000 species and some 35,000 fossil species Very diverse group (snails, clams, octopus) Range from simple organisms to some of the most complex invertebrates

Hawaiian Bobtail Squid

Blue Ringed Octopus

Ecological Relationship Habitats: from tropics to polar region ponds, lakes, streams, surf, ocean depths, etc Most live in the sea Include herbivores, carnivores, and filter feeders

Economic Importance many are food for humans produce pearls (most from Eastern Asia) Some molluscs are destructive (Great Lakes, Snails and Slugs in gardens)

Form and Function Body Plan – consist of head-foot portion (cephalopod) and a visceral mass (nervous system) head-foot portion – contains feeding, cephalic sensory, and locomotion organs visceral mass – contains digestive, circulatory, respiratory, and reproductive organs

Form and Function Body Plan – two folds of skin make up a protective “mantle” mantle houses the lungs and secretes a shell in many species

Form and Function Head-foot – many have a well developed head containing sensory organs range from simple to complex eyes Foot is used for locomotion

Form and Function Head-foot – Unique structure inside mouth called “radula” It is a tonguelike found in all molluscs except bivalves (shell fish) Has rows of tiny teeth that point backward It has about 250,000 teeth When protruded, it can scrape, pierce, tear, or cut food material http://www.youtube.com/watch?v=mLVDwl rSq5U&list=TLDlxJTSuqf42kySqHbo0jexNd vt3BkIqS

Form and Function Head-foot – Foot can be adapted for locomotion, attachment, or a combination of functions Some modifications include – “hatchet foot” of bivalves, funnel for jet propulsion in squids and octopi

Form and Function Visceral Mass – (mantle and mantle cavity) mantle – the outside of the skin extending from the visceral hump that runs down each side of the body, protecting soft parts and creating a space

Form and Function Visceral Mass – (mantle and mantle cavity) mantle cavity – houses respiratory organs products from digestive, excretory, and reproduction systems empty into the mantle cavity in aquatic species, surface cilia create water currents that continually flush out waste

Form and Function Visceral Mass – Shell (when present) typically has three layers outer layer Composed of a protein called “conchiolin” Growth only occurs at the edge of the shell middle layer Composed of densely packed prisms of calcium carbonate in a protein matrix Inner layer Composed of calcium carbonate sheets laid down over a thin protein matrix This layer is continuously secreted by mantle surface, so it becomes thicker during the animals life Calcium for the shell comes from environmental water, soil, or food

a. Outer layer b1. middle layer b2. Inner layer

Form and Function Internal Structure and Function – there is an open circulatory system pumping heart blood vessels blood sinuses closed circulatory system

Form and Function Internal Structure and Function – Digestive tract is highly specialized according to feeding habits Most have a pair of kidneys Ducts of kidneys in many forms serve to discharge eggs and sperm

Form and Function Internal Structure and Function – Nervous System consists of several pairs of ganglia (nerve cells) with connected nerve cords Most molluscs are dioecious Some are hermaphroditic

Mating Leopard Slugs https://www.youtube.com/watch?v=FhVi4Z6CjZk

Class Polyplacophora: Chitons are somewhat flattened and have a surface that bears eight plates, or valves name means “bearing many plates” most are between 2 and 5 cm commonly occur on rocky surfaces in intertidal regions if detached, they can roll up like an Armadillo for protection Sexes are separate

Class Gastropoda (gastro – stomach, podos – foot) By far the largest and most diverse class Contains about 40,000 living species Includes snails, limpets, slugs, whelks, conchs, periwinkles, sea slugs, sea hares, sea butterflies, etc. Often sluggish, sedentary animals Because of heavy shells and slow locomotion organs

Snails

Snails

Limpets (Owl Limpet)

Limpets

Slugs

Whelks

Whelks (Lightening)

Conchs

Conchs

Conchs

Periwinkles

Periwinkles

Sea slugs

Sea slugs

Sea slugs

Frosted Sea Slug

Sea hares

Sea hare

Sea hare

Sea butterflies

Class Gastropoda Basically bilaterally symmetrical, but because of “torsion,” the visceral mass is asymmetrical Torsion – a twisting process that occurs during development

Class Gastropoda Three subclasses – Prosobranchia (largest) Almost all marine Periwinkles, limpets, whelks, conchs, abalones, slipper shells, oyster borers, rock shells, cowries Opisthobranchia Sea slugs, sea hares, nudibranchs, canoe shells Pulmonata Mostly land and freshwater snails and slugs Usually have two pairs of tentacles

Nudibranchs

Nudibranchs

Class Bivalvia (two-shelled) Includes mussels, clams, scallops, oysters, shipworms Most are sedentary Unlike gastropods they have no head, radula, and little cephalization

Class Bivalvia Most are marine, but many live in brackish water and in stream, ponds, and lakes Their two shells (valves) are held together by a “hinge ligament” “Adductor muscles” work in opposition to the hinge ligament and draw the valves together Zebra mussels

Zebra mussels (Lake Mead)

Preventing Mussels in Idaho https://www.youtube.com/watch?v=J4EVAy8ad Mk http://www.youtube.com/watch?v=T18E58vOTu s

Class Cephalopoda most complex species include squids, octopuses, nautiluses, cuttlefishes All are marine All are active predators Have an odd body plan Develops as the embryonic head and foot become indistinguishable The ring around the mouth bears arms and tentacles

Class Cephalopoda Range from 2 to 3 cm to 13 meters

Giant Squid

Slash marks from Giant Squid

The Search for the Giant Squid https://www.youtube.com/watch?v=EbubjXsA4S4

Class Cephalopoda Most have special pigment cells called “chromatophores” in their skin By expanding and contracting, they produce color change Some color change are for protection to match the background Most change is behavioral, associated with alarm or courtship Many deep-sea squid are bioluminescent When the animal is alarmed, it releases a cloud of ink through the anus to form a “smokescreen” to confuse an enemy

Squid

Mimic Octopus and others https://www.youtube.com/watch?v=t- LTWFnGmeg&feature=related

Octopuses

Octopuses

Octopuses

Blue Ringed Octopus The most venous octopus. This small mollusc lives in warm, shallow reefs off the coast of Australia, new Guinea, Indonesia and the Philippines.  It has a life span of about one and a half years.

Blue Ringed Octopus It is said that the venom of this octopus could kill 26 adults in just a few minutes. There is no antivenin for treatment. Fortunately, these octopuses do not attack humans. Injury typically occurs when a blue-ringed octopus is stepped on or picked up.

Nautiluses

Nautiluses

Nautiluses

Cuttlefishes

Cuttlefishes

Cuttlefishes