Friday, 23 November 2012

CLAMS IN ACTION!

Check out this short video on clams! It's interesting to see the muscular foot in action!

Click here:
Moving clams

Thursday, 22 November 2012

EXTERNAL AND INTERNAL FEATURES OF A CLAM


 We have observed external and internal features of clams. We have identified the dorsal and ventral sides of the shell. On the ventral side there is a small bump which is the oldest part of the shell, it is called the umbo. There is also a hinge ligament which joins the two valves together. The hinge ligament allows the valves to open and close. It is softer than the shell so it doesn't crack. We also saw the growth rings on the shell that indicates its age.
The first thing we saw when we opened the shell were the adductor muscles. These are used to open and close the valves. If we pull them off, muscle scars are left on the shell. You can often see the adductor muscle scars on the shells when you eat molluscs! We also located the muscular foot used to move and to bury itself into the sand. We saw the mantle, a fine membrane that covers the mollusc and the gills used to breathe. The gills are easy to recognise because of the folds they have to increase the respiratory surface. We also located the incurrent and excurrent siphon. If you look carefully at the photograph you can see the parts.

Wednesday, 21 November 2012

Nudibranch - marine gastropod molluscs

Check out this video on nudibranch! Nudibranch are marine gastropod molluscs with no shells. They are noted for their stunning colours and forms.

Click here:
National Geograpic video on nudibranch

Tuesday, 20 November 2012

IDENTIFYING MOLLUSCS

Molluscs are invertebrate animals. Most are aquatic e.g. mussels, clam, squid, cockles, cuttlefish, whelk etc. Others, like snails and slugs are terrestrial. Their main characteristic is that they have a soft body and a shell.The body has three parts: a head that contains sensorial organs, a main body part, that contains the main organs and a muscular foot, they use to move or to bury themselves in the sand. Shells can be made up of one or two parts called valves or can be internal. Some molluscs don't have a shell, e.g. slugs. Aquatic molluscs breathe through gills and terrestrial through lungs. Most molluscs are hermaphrodites.

Variety of molluscs

Molluscs are divided into three groups:
Gastropods: They have a spiral shaped shell with only one valve.
Bivalve: They have a shell with two valves.
Cephalopods: They have an internal shell.

We have observed a variety of molluscs in the class, identified them and also identified the group they belong to.
Here are some of the molluscs we have seen.

Razor clam - Bivlave
Snail - Gastropod

Cockle - Bivalve

Whelk - Gastropod


Whelk - Gastropod

 
Mussel - Bivlave

Clam - Bivalve

Scallop - Bivlave
Did you enjoy the experiment?