Threadworms (Heteromastus filiformis) are very thin, thread-like worms that are red in color. They are annelids (i.e., segmented worms). They eat mud, digest the organic matter and excrete the remainder as casting on the surface. These castings are easily visible and give you a feel for the abundance of this spp. Their red color comes from a type of hemoglobin. Just like the hemoglobin in our own red blood cells, it is used for oxygen transport. The worms penetrate into the anaerobic layer of the sediments (note the color difference between the aerobic and anaerobic layers) and must transport oxygen to survive.
Blood worms (Glycera spp.)
Another annelid, that is red or pink in color, but much larger than the thread worms ( up to 30 cm long). The tail has 2 bristles and the head has a large proboscis with 4 black jaws. Be careful of the jaws, it may bite you. It is sometimes called a "beak thrower" because it can extend its jaws very quickly to catch its prey. It eats small animals and plants. They are often dug by fishermen for use as bait.
Razor Clams (Ensis directus)
A long, narrow clam that can be up to 25 cm long. It resembles an old-fashioned straight razor, hence its common name. There are many broken shells on this beach therefore, there must be a large colony nearby. They are generally found on sand or gravel beaches in the lower inter-tidal zone. They will be buried a few cm beneath the surface with their siphons extending to the surface. If you come across a patch of beach with many holes (each about 1 cm in dia.) that squirt water at you when you approach, you have found a clam bed. The water is expelled through the siphon as it burrows through the sand. To burrow, it extends its foot down into the sand, enlarges the tip to form an anchor and then contracts the foot, pulling the clam down into the sand. The contraction of the foot expels the water through the siphon. These are edible clams, but they are hard to capture because they can burrow so quickly. If you do find one, try putting it on the surface to watch it burrow. It should only take 15 –2 0 seconds for it to disappear completely.
Soft Shelled Clams (Mya arenaria)
This is the clam most commonly found for sale in the grocery store. It is also called the Long-Necked clam because its siphon is very long (much longer than that of the razor clam). It is also found buried beneath the sand, but usually much deeper than the razor clams – perhaps as much as 20 cm below the surface. You find colonies the same way as you do razor clams – by looking for holes that squirt water when you approach. They are easier to dig however, because they can not burrow as fast as razor clams. They are often found near fresh water inlets as they prefer lower salinities.
Paralytic Shellfish Poisoning
At certain times of the year and in certain locations in NS; snails, clams, mussels and other shellfish may be poisonous. The toxin comes from a one celled algae called Gonyaulax. This alga contains a toxin called saxitoxin which does not affect molluscs, but is poisonous to people. Shellfish accumulate the toxin as they filter food particles from the water or scrape algae off of rocks. Gonyaulax usually reaches its peak population in June to August and this is when the possibility of shellfish poisoning is most likely. However, blooms of Gonyaulax have been observed as early as March and as late as early November. These blooms are known as the "Red Tide" as the algae are red in color and may be numerous enough to actually color the water. Here in NS, the lower Bay of Fundy is perhaps the worst location for red tides.