Day 11 Mollusca
Phyla Mollusca
The phylum Mollusca includes animals like snails, clams, octopuses, squids, etc
-There are more species of Molluscs in the ocean than any other phylum.
-There are over 200,000 species of Molluscs
-The only phylum that has more species than that is the Arthropods on land
Molluscan characteristics
-Two part body
-Head/Foot and Visceral mass
-Ventral, muscular foot used for locomotion
-Mantle that secretes a calcareous shell and covers the visceral mass
-Mantle cavity functions for all excretion and exchange
-Bilateral symmetry
-Trochophore larvae
-Coelom reduced to cavities surrounding the heart, nephridia, and gonads
-Open circlatory system in all but the cephalopods
-Have a radula
-Most have gills
-Land molluscs need to stay wet or moist
Watch this video on the phyla Mullusca. Create a box in your sketchbook, title it "The Phylum Mollusca" and take notes, write down interesting things that you learn from the video and include an image in your sketchbook. Make sure you understand the characteristics of molluscs and what they are.
Molluscs have a tongue called a Radula
Molluscs have Trochophore Larvae
Classes of Mollusks
These are the classes of molluscs we focus on in this class.
-Class Bivalvia- Hinged between two shells, clams, mussels, oysters, scallops
-Class Gastropoda- Body distorted by torsion when there is a shell, Slugs, snails, Nudibranchs, Limpets
-Class Cephalopoda- Tentacles and siphon, squids, octopuses, cuttle fish, and the nautilus
Other classes of molluscs
-Class Caudofoveata- Worm like deep water marine molluscs with a cylindrical shell
-Class Aplacophora- Lacking shell, mantle, and foot, worm like marine borrowers
-Class Polyplacophora- Have eight dorsal plates, Chitons
-Class Monoplacophora- Single arched shell, Neopilina
-Class Scaphopoda- Inclosed in a tubular shell, has tentacles, Dentalium
Classes of Molluscs
Class: Gastropoda (Stomach foot)
-Largest group of molluscs
-75,000 species
Common Name for all gastropods is Snail (Gastropod)
Orders of Snails
Order: Vetigastropoda
Order: Caenogastropoda
Order: Heterobranchia
The only land Mollusks are in the class Gastropoda (Stomach Foot)
The land Gastropods are the Snails and Slugs
Snail Anatomy
-Slugs are very similar to snails except their mantle does not excrete the material for a shell
-The shell is greatly reduced and under the skin
Because the shell of a snail only has one opening their body plan is twisted. This twisted body plan is called torsion
Watch this video on slug sight
-Snails and Slugs eat leaves and plants. People do not like to have them in their garden because they will eat their plants. One easy way to kill slugs and snails in your garden is beer
-Snails and slugs love yeast. If you put out a cup of beer in a garden the snails and slugs and smell it. They are attracted to the smell and come "running"
-The snails and slugs drink as much of it as they can. They start to get drunk and usually fall in. Once inside the beer they cannot swim and drown
Video:
Snails are hermaphrodites and have complex mating behaviors
-They have long courtships where they dance with each other
-Some snails can be very choosy about their mate
Watch this video on snail reproduction. Create a box in your sketchbook, title it "Snail Reproduction" and take notes, write down interesting things that you learn from the video and include an image in your sketchbook. Make sure you understand the matting behavior of snails.
Watch this short video on leopard slugs
The Zombie Snail!
A Platyhelminthes Trematode that infects snails and takes over their brains
The following material is from Marine Biology. If you already took Marine Biology, look over the material as a review. If you have not taken Marine Biology look over and study the material.
For more in depth info on marine molluscs visit these David Bird Science pages in Marine Biology
Order: Patellogastropoda
Common Name: True Limpets (Gastropod)
Order: Haliotidae
Family: Haliotidae
Common Name: Abalone (Gastropod)
Order: Nudibranchia
Common Name: Nudibranchs or Sea Slugs (Gastropod)
Some times called sea slugs
-Eat sponges
-Are usually poisonous
-Sometimes save the nematocysts of cnidaria that they have eaten and can then use the venom
-Lost their shell. Their mantel no longer creates a shell
-Have exposed gills
Class: Bivalvia (Two Valves)
(Too many different orders)
Common Name for all bivalves is Clam
-Clams
Family: Mytilidae (Type of Clam)
Common Name: Mussels (Bivalvia)
Family: Ostreoidea (A type of Clam)
Common Name: Oysters (Bivalvia)
-Parts
-Umbo- oldest part of the shell
-Adductor muscles- used to close the valves
-Byssal threads- used by mussels to attach to things
Class Cephalopoda (Head Foot)
Order: Sepiida
Common Name: Cuttlefish (Cephalopod)
Order: Octopoda
Common Name: Octopus (Cephalopod)
Octopuses and Squids use a siphon as a jet to propel their bodies through the water
The Cephalopods are masters of disguise
-Their skin has chromatophores that change colors
Video:
Order: Teuthida
Common Name: Squid (Cephalopod)
Order: Nautilida
Common Name:Nautilus (Cephalopod)
