Mollusks – a phylum of animals “Soft bodied invertebrates”

Main Phyla of animals Animal : Plant : Fungi : Protist : eubacteria : archeabacteria Cnidaria Echinoderms Mollusks Arthropods Vertebrates Cephalopods Crustaceans Bivalves Gastropods Bird Insects mammals Arachnids Fish

What makes a MOLLUSK a mollusk All mollusks have a soft body with no skeleton at all. Some mollusks have a shell to protect their soft bodies… but some don’t They have a fleshy “foot” …sometimes several

Three Classes of Mollusks (mollusk = phylum of animal kingdom) Bivalves Gastropods Cephalopods

Cephalopoda (head foot)

Cephalopod anatomy

Giant squid

Giant squids

Nautilus – only shell making cephalopod Has about 90 tentacles!!!! The inner chambers of the shell act as a swim bladder

Cuttlefish Think: Squid with a cuttlebone in it Cuttlebone is not a “bone”… it’s an internal shell that is filled with tiny air pockets (think Styrofoam)

Bivalves – 1st class of mollusks Bivalves = 2 sides hinged Clam Mussel Oyster Scallop

Bivalve anatomy Bivalves flow water into & out of their shell, gills do the gill thing, & they also filter the water – eating algae & waste from the water.

Oyster reefs Oysters build on each other, saves in making the second shell sometimes! 1 oyster filters 50 gallons of water per day

Less Oysters = dirty water One adult oyster filters 50 gallons of water/day Galveston bay use to be filtered through oysters once every week by huge oyster reefs Oysters are harvested for food a lot. Oyster populations have declined Water is not naturally filtered as much. Oysters have to live 3-4 years before mating so it can’t be fixed real fast.. But it can be fixed.

Gastropoda = “stomach foot” (2nd class of mollusks)

Gastropod shell diversity

Gastropod anatomy

What do snails eat? Most snails are herbivores- eat algae Some snails eat dead things – detritus But some can be predators.

Cone snails

Killer snails

Cone snails hunting Net hunter (not a harpoon, general sedative) http://www.youtube.com/watch?v=UHiGuquJmpE National geographic video http://www.youtube.com/watch?v=BMOSvz5mThM&feature=related Nemo eaten by a snail http://www.youtube.com/watch?v=opwGG9_oOjA&feature=related Fish stabbed and swallowed http://www.youtube.com/watch?v=EB9OIUQMGd4&NR=1

2 general ways for Mollusks to reproduce Bivalves Broadcast spawn – never meet (common in most fish) Gastropods & Cephalopods Modified reproduction A packet is passed

Bivalves – the strangest reproduction Example : freshwater mussel Lives in almost all rivers, lakes and streams in this country! INFECT most fish in all rivers, lakes and streams

How do they get in the fish? Most common… just passively by fish breathing water

Gastropods = true hermaphrodite What is the most common fact known about snails/ slugs (not the salt thing, even more basic … ) Most are hemaphrodites.

Cephalopods While their skin is most interesting… they have unusual reproduction. – it is basically invitro fert. Male only delivers a packet Female stores it in a special pouch Female can choose later which packet to use!

Now – for something entirely new the Nudibranch (naked gill) A Nudibranch is a gastropod that has abandoned its shell.

What is a nudibranch? A nudibranch is a sea slug that eats coral/jellyfish.