Videos: Molluscs on our shores

While the tides goes too high for us to explore, I decided to plough through my folders and check out the videos that I took on my trips. Here's a few of them for the first series - molluscs (bivalves, gastropods, cephalopods). These videos are taken on the intertidal zones!

Bivalve locomotion - to observe a bivalve in action takes a whole lot of patience and waiting. Not all the bivalves we encountered were this active. Bivalves tend to be partially or fully buried in the substrate or tightly shut to protect against predation. This video shows that bivalves generally use their large foot (the muscle sticking out of the shell) to translocate from one place to the other. They generally do a leaping action while others drags the shell across the area.



Japanese bonnet snails - a beautiful yet lethal snail. They feast upon echinoderms, especially the cake sand dollars common on our shores. The shell is well thickened and protects against potential predators and dessication. The long snout sticking upon the water is likely a siphon. Try spotting the eye spots and antenna.



Marginatus conch snail - a close relative to the other commonly known Strombids, this snail was fairly recently described by Chim et al. (2009). This taxonomy of this snail is rather complex and we have been notified that the name has been changed (again!) to Margistrombus robustus (G.B. Sowerby III, 1875). A fairly uncommon conch snail, usually 3-4 individuals on each sighting. Like any other conch snail, the righting behaviour is very interesting and captured in the following video.



Olive snail - long cylindrical shape, it allows the snail to penetrate substrate like a bullet. Check out the snail 'hammer-head' shape mantle and observe its movements.



Noble volute - one of our large gastropods, growing up to 20cm shell length. This is a common resident on many of our sandy shores. I still recall that my first encounter with this snail was someone harvesting it home to eat! Oh my! This one surprised by 'rising from the sand' beside my feet. haha...



Reef octopus - a very smart and efficient predator. One of its characteristic is the morphing of its chromatophores into various backgrounds. This individual here was displaying warning coloration to fend off its predators (aka humans in this case). Finally, usually the last resort would be to squirt ink and propel itself away from dangers.



Next series: Echinoderms