We have two contributors today. First, some marine lovelies from Jacques Hausser in Switzerland. His notes are indented:
I’m just back from Britanny. Switzerland is a landlocked country and we lack close contact with the sea. Thus each spring we organize an optional two weeks internship on coastal ecology and faunistics at the Biological Station of Roscoff for the masters students in ecology and evolution. I started it forty years ago and I still happily contribute, ten years after my retirement. It is always an happy moment, turning up boulders, shoveling and sieving sand, helping students identify the collected animals – and also enjoying local seafood, cider and pancakes. Here, in a perfect taxonomic disorder, are some photos of our findings taken in the lab—I tried to suppress any backgrounds.Yes, it is an animal, and more, a mobile one. The rosy feather star, Antedon bifida, is a Crinoid, a very ancient class of the phylum Echinodermata (sea urchins and starfishes). It usually clings on the rock or on an alga with the longish hooks (cirri) under its central part. You can distinguish some of them between the ten arms. But it is able to swim if necessary with alternate movements of its arms (https://www.youtube.com/watch?v=O2zzv8LHjcw). As with many marine animals (and unlike any terrestrial one), it is a suspension feeder: it catches small particles in the water and they are brought to the mouth along a ciliated groove in the underpart of the arms.
It doesn’t look like one, but the tiny broad-clawed porcelain crab, Porcellana platycheles, is a filter feeder. It maintains a water current by permanently waving its mouthpieces, and filters its food with long setae (bristles). Its impressive claws are used only in territorial (and sexual ?) competition. Quite flattened, it lives mostly under stones. And, by the way, it is not a crab (Brachioura) but a relative of hermit crabs and squat lobsters (Anomaloura). Easy: only 3 pairs of visible walking legs and long antennae.
Compare with a real crab, the hairy crab, Pilumnus hirtellus: four pairs of walking legs and very short, almost invisible antennae. This small, omnivorous species is found mainly in the holdfasts of laminarian algae and is probably very “misocrabic” or at least territorial: I have never found two of them in any given holdfast.
The smile of the sap-sucking slug, Elysia viridis, an Opisthobranch mollusc. Algae don’t have sap, as far as I know). It feeds on green algae, specially Codium, and, interestingly, is able to spare the chloroplasts of the alga and tosequester them in the cells of its back, where they continue to photosynthetize for the benefit of the slug. The “ears” are rightly called rhinophores (nose-bearers), they detect smell rather than sound. You can see the tiny eye just behind the left one. Although this individual is rather contracted, you can also distinguish the small iridescent blue spots that adorn the animal.
I call it “Mister No body”. Nymphon gracile is a Pycnogonid or Sea spider, and actually a very remote cousin of spiders and scorpions, a Chelicerate (or even possibly a sister group to every other arthropod). It has so little space in his body proper that its digestive tract must expand itself into the legs. It is a rather eclectic predator, eating sessile prey like sea squirts, sea anemones and other hydrozoans, and even snail eggs. This one is a male: you can distinguish the faintly visible translucid ovigerous legs used to carry the eggs (yes, it is the male’s duty in this species).
It is mesmerizing to observe the movements of the tentacles of Eupolymnia nesidensis, a polychaete worm of the family Terebellidae. They seem absolutely autonomous, exploring every aspect of their environment, retracting, expanding, changing direction or sticking to the substrate with a very good imitation of free will. They are U-shaped in section, which forms a ciliated canal along which tiny particles of food are brought back to the mouth. The red “bushes” are gills used for the respiration, and between the gills and the tentacles you can notice a collar of tiny black eyespots. The worm lives in a self-made mucous tube glued under a stone and encrusted with gravel and sand.
It is not as spectacular as its exotic cousins we have recently seen on WEIT, but I nevertheless like the tiny Limacia clavigera, the orange-clubbed sea slug, is a nudibranch mollusk. It browse on sea mats like Electra pilosa and probably sequesters some toxic molecules from its prey into the yellow-clubed “cerata” each side of its body (a frequent habit in sea slugs with aposematic warning colors). It is able to autotomize these cerata to distract a would-be predator (examples of reduced cerata on the left side), but they regrow in a few days. Notice the rasp-like rhinophores and the three tiny yellow gills between the forelast pair of cerata.
Tritia reticulata, the netted dog whelk (formerly called Nassa reticulata, Hynia reticulata and Nassa reticulata again – the lack of stability of the zoological nomenclature sucks). It is a necrophageous snail, the real vulture of the beach. With its long respiratory siphon, it looks like a vintage steam engine, but the siphon is very useful considering its habit of burying itself in the sand. It is able to detect any dead animal a long distance away (at least one meter in an aquarium) and reacts very quickly. Note that the eye is at the basis of the tentacle, not at the tip like in the terrestrial snails.
And reader Christopher Moss snapped some snowshoe hares in his Nova Scotia garden. They’re changing color back to their warm-weather fur, so are appropriate to post today.
Two new visitors today, Lepus americanus, which I have not seen in the garden before. One is beginning to recover the brown hair of summer, and the other is still pretty much a pure white. They are sitting in the same spot, but are two different creatures! First the white one came along and had a sniff at some branches.
The the brown flecked one turned up. Lovely!
Playing hide and seek with me:
