Invertebates Molluscs Ch. 7

Objectives

Body Structure phylum Mollusca More species in ocean than any other animal group (over 200,000) Soft body in a calcium carbonate shell – Many variations on this Mantle – Thin layer of tissue that secretes shell

Body Type Foot – Muscular, used to move Radula – Unique to molluscs – Made of chitin – Ribbon of small teeth

Blood Sucker! Cooper’s nutmeg snail prey on electric rays Extends its long proboscis Makes a tiny cut in the rays skin with its radula Sucks the blood out

Types of Molluscs: Gastropods Largest, most common, and most varied group 75,000 + species, mostly marine Snails, limpets, abalones, nudibranchs Limpet with barnacles

Nudibranchs Huge variety— species Blind Prey on stinging creatures Store prey’s sting and recycle it in their own defense through feather plumes (also gills) Lifespan is several weeks hermaphrodites

Types of Molluscs: Bivalves Clams, mussels, oysters, and more Two valves, or shells Filter out small food particles from the water Abalone Giant Clam, Palau

Oysters and Pearls Oyster secretes layers of calcium carbonate to coat irritating particles or parasites in the mantle Cultured pearls are obtained by inserting a tiny bit of shell or plastic into the mantle

Cephalopods Octopuses, squids, cuttlefishes, and others Active, complex nervous system Agile swimmers Foot modified into arms & tentacles – “cephalopod” translates to head-footed Large eyes, similar to ours

Cephalopods Lack a hard shell (except for the chambered nautilus) – Squid and cuttlefish have hard shells inside the body All are carnivores All have a mantles Eyes have cornea, lens, and retina

Octopuses: How They Move Jet propulsion! Move by taking in water to the mantle then forcing it out the siphon – Siphon points all directions Can move up to 25 mph

Octopuses: All sizes

Can change shape

Can Change Color

Ink used to distract predators

Great Hunters: a built in Swiss army knife Retractable beak (similar to a parrot’s) – Breaking open clam shells and tearing flesh Radula – Used to scrape animals out of shells Salivary Papillas – Drills into shells – Secretion erodes shell and weakens prey

Octopus vs. Shark

Chambered Nautilus Lives 400 m deep, but ascends up to look for food at night Contains gas filled floatation chambers in shell Closest relatives are squid and octopus Tentacles have chemical sensors—detecting predators and prey Eats once a month

Cuttlefish There actually not fish at all. Let’s watch a movie…

Squid Known for speed and agility Use jet propulsion – Up to 23 mph, 12 feet out of the water Live years Swim in schools (unlike other molluscs) 10 arms, two are tentacles

The Vampire Squid Vampyroteuthis infernalis Found in tropical and temperate regions Ear-like fins Only about 6 inches long Live at a depth of 3000 ft. Has tooth-like spikes on its arms

The Humboldt Squid Also known as jumbo squid or red devils Up to 6 ft and 100 pounds Live between 600 and 2200 feet deep 1-2 year lifespan Cannibals Very aggresive

Beak and Suckers Suckers have hooks and teeth Razor sharp beak

Dive with Humboldt Squid

GIANT Squid Largest: 59 ft long, 900 kg (just under a ton) Biggest invertebrate on earth Largest eyes in animal kingdom (10 cm across) Deep sea is their home

That’s a big, dead squid! Washed ashore, NZ, 1996

Mysterious… First time photographed alive was in ,950 feet down in the North Pacific Ocean in Japanese waters

Giant Squid footage

Giant Squid vs. Sperm Whale Remains of Giant Squid often found in Sperm whale’s stomachs Marks made by squid suckers have been seen on whale skin Let’s watch a movie