Posts Tagged 'crabs'

Sand Crab

Emerita talpoidaThe Atlantic Sand Crab (Emerita talpoida) is also known as the mole crab and the sand flea (confusingly, since there are, in fact, amphipod sand fleas).Emerita talpoidaThese streamlined animals are, at any rate, crustaceans. As Sarah Oktay explains from the place I first came across them, they are surf-zone specialists, and pretty important in that harsh habitat. Emerita talpoida

Hermits

Ilyanassa obsoletaI believe these are Eastern Mud Snails (Ilyanassa obsoleta), which look like rocks until you look closer. There are quite a few of them in Jamaica Bay. And some of them were moving much too quickly. They were, in fact, hermit crabs, who use found snail shells for their own.hermit3Hermits don’t have protective shells like your usual crab species; they use snail shells instead, swapping to larger ones as they grow.hermit2This article argues that hermit crabs populations are going quite well because of a surplus of shells to choose from, from the introduced Common Periwinkle (Littorina littorea) which has spread up and down the East Coast. (Periwinkles generally like rocky shores, so the New York estuary doesn’t seem to have many of them.)Hermit1I don’t know the species here. Anybody?

Hermit crabs from the Caribbean, rather larger than these, are exploited by the aquarium trade, and as a result, the internet is full of wails of children of all ages bemoaning their dead and dying “pets.” As animals wrenched from their own habitats (these are usually land crabs like the “Purple Pincher”), they potentially threaten local species and other crustaceans with diseases.

Variations on Legs

fiddlerFiddler crabs in the tiny patch of ever-so-green right now salt marsh at Pier One. On the jumbly rocks next to it, a number of these spiders:spiderI have returned from a two week trip abroad. I have a new computer. I am ready to blog again.robinA young New World Robin, SO different from the Old World ones, as pictured yesterday.

Dead Horse Bay

Yellow-rumped warblers and Green Darner dragonflies before we got to the landfill edge.One of two Royal Terns, Thalasseus maximus, both with bands on their left legs. Not a commonly sighted bird in the city; I didn’t know what they were at first. The smaller Common and Little Terns we see here during summer have already gone south. These Royals sound quite different from our regular terns, and one of them was excreting a lot. I later read that they defecate around the sides of their scrapes (nests) to build up a a hard rim of guano, possibly as a defense against minor flooding on the low-lying islands they breed on.The Asian or Japanese Shore Crab, Hemigrapsus sanguineus. Found about a dozen washed up on the beach perpendicular to the Gil Hodges Bridge. Three spines on each side of the carapace, red spotted claws, dark bands on the legs are your field marks for this invasive. Not good news for already fraught Jamacia Bay (Dead Horse being a nook on the north side of Jamaica Bay, if you haven’t wandered its singing glass beach.)

We’ve Got Crabs

The triangle of saltmarsh ot the southern end of Pier One at Brooklyn Bridge Park is an experiment. It’s cordgrass (Spartina alterniflora), which thrives even though it’s flooded by salt water at high tides. In flower now, it will send many seeds off on the currents, searching for mudflats. Key to its success, though, is the matrix of roots in the mud. Two other keys are ribbed mussels and fiddler crabs; together the three species anchor an incredibly productive and important ecosystem, nursery for many fish species and acting as kidneys by cleaning water.

Now, neither the mussels nor the crabs were “planted” with the cordgrass when this went in two years ago. That’s what I mean by experiment. But the fiddler crabs (Unca pugnax, I think) have found the marsh. Could there be mussels in there as well? This is a male; I also saw one female. Females lack the big bull-fiddle claw, which the males used to show off and protect their tunnels. Now I only saw two individuals, and places like Four Sparrow and Pelham bay are absolutely scurrying with them (these two observed at high tide, mind you), but everybody starts small. UPDATE: returning four days later at lower tide, I saw several more and their tunnels; they sense your vibrations as you approach and hide just before you get a good look at them, so try sitting on the rocks and waiting until they emerge again.Just a few feet away, I found evidence of a second species of native crab, the Blue or Blue Claw (Callinectes sapidus). The Hudson has a robust population of this species, according to this. This was a young one, 1.75″ long. Being delicious, it has been scarfed up by something; those are additional bits of chitinous remains above the overturned carapace. Those points on the sides of the carapace are tell-tale for this species.

[Crab and crab shell were photographed in the water. Image may thus appear larger than is actually the case.]

Sheepshead Bay

Ten piers, ten local creatures of the sea.

Pelham Bay Park

“Only the dead know Brooklyn…” but you can say the same thing for the rest of NYC. Five massive boroughs: it’s a full-time job to explore them all. Last Saturday, we journeyed up to the eastern Bronx to visit Pelham Bay Park. Pharaoh — or should I say “Tyrant,” based on the Greco-design of the bathhouse — Robert Moses had Orchard Beach built there in the late 1930s from sand barged up from dredging in the Rockaways. He — of course I mean his workers — merged a small peninsula of the Bronx, Rodman’s Neck, to several rocky islands with a mile-long arc of beach facing Pelham Bay. The resulting “Riviera of the Bronx” should be experienced just for itself: this is da Bronx letting it all hang out, papi.

He didn’t seem to be trying to separate the Ring-billed from the Herring gulls.

Just west of the beach is parking for 6,8000 cars — Jesus freaking Moses! — but we ventured up on the 6 train and the Bx12 bus, a long trip but well worth it. (Unfortunately, the bus only runs in summer.) Hunter’s Island north of the beach has some nice, but we thought haphazardly marked, trails. Considering the number of people on the beach, there were only a few in the woods, although the salsa from the beach could be heard throughout. This is a fine stretch of mature oak-hickory forest (alas for the chestnuts!), with patches of white pine, and remnants of John Hunter’s mid-19th century estate garden. Cabbage White butterflies were absolutely everywhere in the woods, from the path to the upper canopy. We passed three broken robin’s eggs on the path. But wait! With this great forest, you also get: the rocky shore of Hunter and it’s neighbor, Twin Island. This is Hartland Formation schist, a convoluted gneiss, with numerous quartz veins, one of the bedrocks of the region that looks amazingly tortured in places. Where it meets the water of Long Island Sound, the rock is smoothly worn away by long erosion. For those of us from Brooklyn, which is made up of chaotic piles of glacial till, or rubble, the exposed bones of the earth here are evidence of the great drama of regional geology.We found our old friends, Spartina cordgrass, ribbed mussels, and fiddler crabs, anchoring expanses of tidal salt marsh. All the rocks meant blue mussels as well, much paler specimens than I’m used to. Long Island Sound is rife with invasive species, and we found one of them, the Asian or Japanese Shore Crab (Hemigrapsus sanguineus). This trio was sun-bleached.

The mudflats were well-patrolled by several Great and and few Snowy egrets and half a dozen Black-crowned Night herons. A single Great Blue Heron also rose up on its six foot wings. They should eat more invasive crabs! unfortunately, these crabs like rocky habitats, not mud flats. In all, we saw about thirty species of birds. The ranger at the Nature Center told us that a pair of Great Horned Owls had successfully nested in the area this spring. We didn’t see the birds, but we did luck upon an unusual feather very near to the Nature Center that sure looked raptor-ish. Upon research, it in fact turned out to look a lot like a tail feather from a Great Horned Owl.Inside the Center we came across another Bronx native, an Eastern Box Turtle.Totally unexpected, but where the tide is concerned, one should always expect the unexpected. (This has been the downfall of more than one mobster.) This foot-long American eel (Anguilla rostrata) is probably under two years old, not yet sexually mature, in the process of becoming a “yellow eel” as this stage in its life is called. (UPDATE: That is, if it was alive. It’s an ex-eel.)

The Hunter’s Island Marine Zoology and Geology Sanctuary, to give it its official title, should be on everyone’s list of urban natural history hotspots.


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