Getting Your Nose Bent out of Shape

Bent-nosed Clam (Macoma nasuta)
Side profile of the Bent-nosed Clam (Macoma nasuta) showing the upward bend in the shell.

After a half day inside attending a workshop at the Filberg Lodge in Comox, BC I definitely needed a little fresh air and a nature break. The Filberg sits right down on the water in Comox, with a fine view of Goose Spit across a shallow muddy bay. The tide was low in the late afternoon when the workshop ended and the weather was an unstable mix of sun and clouds threatening rain. The light was spectacular.

The beach at this part of Comox Bay is a mix of fine mud and gravel littered with the remains of the creatures that live here. Littleneck clam shells abound and no matter how careful you are the empty shells crunch underfoot. Most of the clam shells are covered with a fine layer of muck and slimy algae. Barnacles grow thick on anything that provides an anchor – clam shells, rocks, wooden pilings, old discarded pieces of metal.

Bent-nosed Clam (Macoma nasuta) - outer shell
The outer shell of the Bent-nosed Clam (Macoma nasuta) showing some of the thin varnish.

As I picked through the Littleneck shells looking for something that wasn’t stained with algae or mud I discovered a small Bent-nosed Clam (Macoma nasuta). This bivalve is distinctive and like the name suggests the shell has a slightly bent shape at the point where the siphon emerges. The Bent-nosed Clam is a native species of clam in British Columbia and can tolerate the fine mud and low oxygen levels present in this muddy bay.

Why is it bent? The Bent-nosed Clam prefers to lie on its side 10 to 15 cm below the surface of the mud. It then sends up its long orange siphons through the substrate drawing water fine sediment and food particles in through the long incurrent siphon and expelling waste water through its excurrent siphon. It slowly moves sideways to a new location when it is done. The bend indicates which side is up and which side is down with the bend of the shell pointing towards the surface of the mud in which it is buried. Bent-nosed Clams retain a lot of sediment making them an undesirable species to harvest.

Bent-nosed Clam (Macoma nasuta) - inner surface
The shiny, white inner-shell surface of the Bent-nosed Clam (Macoma nasuta).

The shell of the Bent-nosed Clam is fairly fragile. The outer shell is mainly white but the remains of a thin brown varnish is visible on most fresh shells. The inner shell is a beautiful white colour and when spread open sort of resembles a pair of elephant’s ears. The upward bend of the shell is distinctive in profile and a sure way to separate this clam from other macomas.

After poking around on the mudflats for close to 45 minutes the light was starting to fade and my feet were getting wet – note that rubber boots are appropriate footwear for mudflat exploration. I’ll be back tomorrow for the second day of the workshop and hopefully will have a little more time afterwards to meet more of the fascinating inhabitants of this interesting ecosystem. I’ll definitely be bringing my gumboots!

You might also enjoy reading this humourous encounter with a Bent-nosed Clam at Rock Paper Lizard.