There were lots of hermit crabs scooting around in the tide pools. A pair of them got into a bit of a scrimmage; actually, one attacked the other, who fought back for a bit then scuttled away, with the larger one in pursuit. They were in shells of the same species, and the crabs too seemed to be of the same species—their “feet” were light-coloured. I wonder what the fight was about. Maybe they were just feeling crabby.
I had fun drawing crabs with the Draw With Me gang. I ate a lot of mud crabs in my feral hippie days, living on tidal flats in the Australian tropics. We had very little money, but had a garden full of fruit trees, a canoe, and a bunch of crab pots, so we ate pretty well.
OK, this is the cutest thing I’ve learned about all week. Tiny, pugnacious pom-pom crabs have very thin shells, and so they use anemones to defend themselves, waving them around vigorously like boxing gloves. I wondered if they put them down to eat, but it seems that the anemones collect food as they are being swished through the water, and the crabs just nibble it off them. Kind of like licking your swiffer I suppose (ugh, gross).
The crab/anemone relationship is symbiotic, though it seems that the crab gets the better end of the deal. If one of its pom poms gets lost, the crab will just tear the other one in half. Each half will grow into a complete organism. Isn’t nature amazing?
So many questions!
The theme for this week’s Draw with Me was lobsters, both “true” and “spiny”.
Although they superficially resemble each other in terms of overall shape and having a hard carapace and exoskeleton, the two groups are not closely related. Spiny lobsters (Palinuridae family) can be easily distinguished from true lobsters by their very long, thick, spiny antennae and by the lack of claws. True lobsters (Nephropidae family) have much thinner antennae, and claws on the first three pairs of legs, with the first being particularly enlarged.
Spiny lobsters are found in almost all warm seas, including the Caribbean and the Mediterranean Sea, but are particularly common in Australasia (where they are usually referred to as crayfish or sea crayfish) and in South Africa.
On the other hand, the American lobster (Homarus americanus)—also known as Atlantic lobster, Canadian lobster, northern lobster or Maine lobster—thrives in cold, shallow waters. I wonder if the claw growth is an adaptation more useful in colder oceans. If so, why?
Striped shore crabs (Pachygrapsus crassipes) live along the west coast of North America, from Baja California, Mexico, to central Oregon. Measuring 4 – 5 cm across the carapace, they can be found in estuaries, tide pools, mussel beds, or scuttling along shoreline rocks. These, and hermit crabs, are the most common crustaceans I see at my local tide pools.
Though they feed mostly on algae and phytoplankton, they are opportunistic and will also eat animals including dead fish, limpets, snails, isopods, worms, and mussels. They will even eat recently molted specimens of their own species. They are prey for seagulls, octopuses, rats, raccoons, and humans.
Though most crabs and many shore crabs spend the majority of their time underwater, P. crassipes is an exception. They apparently spend more than half their time on land, though they typically stay close to the water’s edge.
Spiny lobsters can produce a loud rasping sound by rubbing an extension of their antennae against a rigid part of their body below their eyes. This noise may be used to communicate with other lobsters or to ward off predators.
This was the most intact lobster shell I’ve ever seen at the beach. Sure, it was broken in half and was missing a few legs, but it was mostly there.
hashiworks 