Category: crustaceans

Readers’ wildlife photos

March 12, 2026 • 8:15 am

And we have more photos. Today’s come from Jan Malik, documenting the birds of Barnegut Inlet in New Jersey. Jan’s captions and IDs are indented, and you can enlarge the photos by clicking on them.

My previous batch from the Barnegat Inlet covered geese and ducks. It’s time for some of the other coastal birds now.

Immature Double-crested Cormorant (Nannopterum auritum). In contrast to diving ducks, these birds have no buoyancy problem and submerge easily.

Common Loon (Gavia immer). Judging by the slightly pinkish gape at the base of its bill and the fuzzy transition between black and white, this is an immature bird that stays on coastal bay waters before maturing and returning to quiet inland lakes to breed:

Another loon, this one with a mangled crustacean that I suspect is an Atlantic blue crab (Callinectes sapidus). I wonder if a diving loon preferentially picks a freshly molted crab the way we select ripe fruit:

Not a great loon picture, but we can see enough of the prey’s fins to identify the fish as an Oyster Toadfish (Opsanus tau), a species in which males provide parental care to eggs and young. The fish was big and bony, so the loon struggled a bit to swallow it. That fish would be a terrible choice for performing the Fish Slapping Dance. For the loon, it would be preferable to swallow its catch underwater, because at the surface it may be stolen by gulls, who know where a bird has dived and circle above waiting for it to reappear:

A couple of Savannah Sparrows were hopping on the rocks. I suspect that this pale bird with very little yellow in its brow is an Ipswich Sparrow, a subspecies (Passerculus sandwichensis princeps) that breeds on the sand spit of Sable Island off Nova Scotia:

Three species of shorebirds are common in winter at the Barnegat Inlet, all quite similar at first glance in size and plumage, but each occupying a different ecological niche. First, the Ruddy Turnstones (Arenaria interpres), here trying to sleep—probably using only one half of their brain to watch for predators, in unihemispheric slow-wave sleep. Their bills are short, stubby, and slightly upturned, adapted for—just as their name suggests—turning over beach debris to search for invertebrates hiding underneath:

Next, the Dunlins (Calidris alpina). They feed, roost, and migrate in large flocks. Unlike Turnstones, their bills are long, slender, and sensitive, used for probing tidal mudflats for worms and crustaceans:

Last, there are the Purple Sandpipers (Calidris maritima). Their bills are more “general purpose” than those of the other two species. Their covert feathers do show a purple sheen in the right light:

Purple Sandpipers and Dunlins are not very afraid of people on their wintering grounds; they may rest a few meters from a quiet observer. But the slightest hint of danger can trigger the whole flock to take flight in an instant—only to land nearby a moment later:

Purple Sandpipers are adapted to rocky coasts, where they feed on mussels exposed during low tides and on other invertebrates. The undersides of their feet must have a texture that allows them to walk sure‑footed on slime‑covered, slippery rocks:

 They have also evolved Silly Walks:

A distant Harbor Seal (Phoca vitulina), a frequent sight in the Inlet, always seems to look at the jetty with disappointment when it notices that this prime haul‑out spot is occupied by people:

As I was about to leave, the colors of the sunset behind a distant house caught my attention, so I took a picture, thinking little of it. Only back home—rather like the character in Antonioni’s Blowup—did I realize that the picture hides a predator the sleeping shorebirds must be on guard against. To be honest, I can’t be sure this was a flesh‑and‑blood predator and not one made of polystyrene, but the impression remains:

Readers’ wildlife photos

January 27, 2026 • 8:15 am

This is the last batch I have, so please send in your good wildlife photos. I know some of you out there are hoarding them. Don’t make me beg!

Fortunately, UC Davis math professor Abby Thompson has sent some photos of life in tide pools. Abby’s captions are indented, and you can enlarge her photos by clicking on them.

The weather over New Year’s was stormy; most of these pictures were taken when the rain let up for a few hours.   There are generally fewer creatures visible at this time of year in any case-—the big surge in intertidal species happens in the spring in Northern California.   An exception was one particular species of nudibranch,  Phidiana hiltoni, of which there were dozens for some reason.

Genus Heptacarpus (some kind of shrimp). Not a great photo, but the color is true, and if you look closely you can see she’s carrying eggs:

Superfamily Mytiloidea (some kind of mussel). Tidepools make you very aware of how much we don’t know.  This mussel species moved into my local pools in 2022, and this ID is still the best I have for it:

Pisaster ochraceus (Ochre star) Admiring his reflection:

Pollicipes polymerus (Gooseneck barnacle). The red “lips” on this cluster (common this time of year) I’ve read variously are because of the shade they’re in, the cool weather, high hemoglobin levels, or all of the above:

A baby gooseneck barnacle:

Velutina velutina (velvet shell snail):

Family Ampithoidae (some kind of amphipod). Again not a great photo but the spectacular color is true. The next photo shows the whole animal:

Family Ampithoiuidae:

Phidiana hiltoni (nudibranch) This was the species there were dozens of, with very few other species putting in an appearance:

It cleared up just at sunset one day, for this nice view over Bodega Head:

Readers’ wildlife photos

November 17, 2025 • 6:15 am

Intellectual hero and UC Davis math professor Abby Thompson again has a batch of lovely intertidal photos for us. Abby’s captions and IDs are indented, and you can enlarge her photos by clicking on them:

The first two pictures were taken on my cellphone at the Berkeley marina, where a friend was taking us sailing. Fortunately for me, the boat needed more than an hour of preparation, which I got to spend lying flat on the dock looking at the marine life growing underneath it. There’s an entire community on inaturalist devoted to observations of such “dock fouling”; it’s an incredibly rich environment. Because all I had was my phone, only a couple of the pictures I took were legible- next time I’ll bring a camera (and hope the boat needs even more work).

Clathria prolifera (red beard sponge). Most sponges can’t be identified from a photo, but apparently this brilliant one is an exception:

Genus Ciona (tunicate). Pretty much any blobby thing you see lying around the beach is some kind of tunicate, an animal with an inflow and an outflow, and usually not too much else to recommend them (unlike, say, clams, which are at least delicious). These at the marina were lovely, however, looking flower-like:

The rest of the pictures were taken in my usual spot on the coast, near or after sunset (that’s when the great winter low tides happen). At night it’s cold, wet, slippery and, of course, dark, which makes things a bit tricky.

Genus Crepidula; Slipper snail – this clings to the rock looking almost like a limpet:

Slipper snail top view:

Order Amphipoda; I liked this guy’s eyes:

   Genus Polycirrus; Spaghetti worm- it’s one worm, with many tentacles. The main body of the worm is curled up and coated in sand:

Dirona picta:  A nudibranch, munching on some matching bryozoans:

Cebidichthys violaceus (Monkeyface eel, or monkeyface prickleback) Despite its common name and looks, this is a fish, not an eel (all eels are fish, but not vice versa). Supposedly delicious, it’s one of the creatures for which I regularly see people foraging. They’re caught by “poke-poling”; a baited wire hook is just stuck into the end of a long pole, and the fishing method is to poke the hook into crevices under the rocks.    One of the advantages of nighttime tide-pooling is that there are a few creatures- this was one- that seem to get stunned by a flashlight, and they stay completely still.  In the daylight you seldom see one of these, and they’re gone in a flash, too quick to photograph:

Anthopleura xanthogrammica (tentative) (giant green anemone) Several species of anemone fluoresce like this under UV light:

For the second group of pictures [after number 4] the camera was my Olympus TG-7, in microscope mode, with a lot of extra lights.

Readers’ wildlife photos

May 21, 2025 • 8:15 am

We’re running low on this feature, so please send in some good photos. I won’t beg again for a while.

Today we have photos from Africa by Loretta Michaels.  Her captions and IDs are indented, and you can enlarge the photos by clicking on them.

Brief Introduction: I used to do a lot of business in Africa and so I almost always tried to tack on a weekend safari of some sort while there.  Most of these times I had only my iphone to take pictures, unlike the bigger safari vacations my husband & I take with all our camera gear.

While in Dar es Salaam on business, I spent a weekend on Chumbe Island, just off the coast of Zanzibar.  One of the more bizarre sightings was a Coconut Crab (Birgus latro), the largest land crab in the world, which is able  to climb coconut palms and easily crack coconuts with its claws.  These crabs also eat fleshy fruit and even prey on smaller crabs. This species of crabs has evolved to live on land from the sea, returning to water only to lay their eggs. On land, they live in underground holes made with fibers from coconut husks, and are generally only spotted at night. An adult crab can reach one meter in length. It has a curled-under abdomen that makes it look like a lobster. Coconut crabs supposedly have very tasty meat, so, unfortunately, they are hunted:

Three nicely aligned bush elephants (Loxodonta africana) I saw during a trip to Zambia:

A nice female African lion (Panthera leo), spotted during a night drive in Zambia:

A Komodo Dragon (Varanus komodoensis) spotted during a drive:

Two white rhino (Ceratotherium simum) in Nairobi National Park, a 45 square mile wildlife sanctuary established in 1946 just outside Nairobi:

Lunchtime at the Lilayi Elephant Nursery just outside Lusaka, Zambia.  The baby elephants are just adorable to watch, especially as they come running in from the fields when they see it’s feeding time:

A Golden Monkey (Cercopithecus mitis kandti) spotted in Volcanoes National Park in Rwanda:

A mother and baby mountain gorilla (Gorilla beringei beringei) in Volcanoes National Park in Rwanda, just outside Kigali. It is one of two subspecies of the Eastern Gorilla.  The other population lives in the Congo. The park is one of the 3 homes of the endangered mountain gorillas within the Virunga Mountains:

Dominant male gorilla in Volcanoes National Park:

Variable Sunbird (Cinnyris venustus) in Rwanda. The sunbirds are a group of small Old World passerine birds which feed largely on nectar, although they will also take insects, especially when feeding young. Flight is fast and direct on their short wings. Most species can take nectar by hovering like a hummingbird, but usually perch to feed most of the time:

Readers’ wildlife photos

January 20, 2025 • 8:15 am

Today’s photos come from mathematician and Hero of Intellectual Freedom Abby Thompson of UC Davis, whose avocation is photographing California tide pools and their invertebrates. Abby’s captions are indented, and you can enlarge her photos by clicking on them.

New year’s tidepool pictures from Dillon Beach in northern California, plus a few older photos.  It’s not that much colder during the winter here- August can be freezing, December delightful.   To see much in December you have to be willing to go out after dark, which is a little spooky, but has the advantage that you often get to see racoons foraging on the rocks.    Sadly the only pictures I get of them look like two red dots (their eyes) on a black background.

As usual I got help with some of the IDs from people on inaturalist.

Schuchertinia milleri (tentative):

This is through a microscope, taken with my iphone.  In the tidepools it appears as a small very pink blob stuck to a rock. These are hydroids, closely related to jellyfish, unlikely as that seems.

Kelp crab:

These crabs are one of the few things you should be cautious about in the tidepools here- they are reported to have a strong bite with their claws (I haven’t tested this), and they’re not shy.

The next four pictures are all nudibranchs. As you can see, their coloration is quite varied, but nevertheless they are all the same species. Keep this in mind for when we get to pictures 7,8 and 9.

Triopha maculata 1:

 

Triopha maculata 2:

 

Triopha maculata 3:

 

Triopha maculata 4:

 

Ok, the next two pictures are two distinct species of nudibranch.    To my eye, the difference in coloration here is a bit more subtle than for the Triophas; H. crassicornis has white “stripes” on the frilly stuff on its back.

Hermissenda opalescens:

Hermissenda crassicornis:

And the next picture is of these two local species of Hermissenda hanging out together.  Not exactly in flagrante (nudibranchs spend an awful lot of their time mating and laying eggs), but still, looking pretty friendly. Maybe Jerry will chime in with some info on delimiting species?  and how exactly it is done, for us non-experts. [JAC: two different forms copulating doesn’t resolve their species status!]

Hermissenda opalescens and Hermissenda crassicornis:

Clam siphons:

There is not enough appreciation of bivalves in the world, except as dinner,  Their siphons can be lovely (I admit this may be in the eye of the beholder).

Coryphella trilineata:

A pretty nudibranch. There are lots of this species at the moment.

Pycnogonid stearnsi:

There are several species of “sea spiders” locally.   They’re small (this one was less than an inch across), and lively.      This is the most common here.

Anthopleura artemisia (Moonglow anemone):

You may remember from earlier pictures that this is another species with many dramatically different color variants.

Camera info:  Mostly Olympus TG-7, in microscope mode, pictures taken from above the water.

Readers’ wildlife photos

December 18, 2024 • 8:15 am

Today we have some underwater photos from reader Peter Klaver. His captions and IDs are indented, and you can enlarge his photos by clicking on them.

My friends and I did 5 days of scuba diving from San Pedro in Belize. The coral reefs there are beautiful and are home to many animals.

The large animals we saw most often were nurse sharks (Ginglymostoma cirratum):

They are quite tame and if we spotted them lying on the sea floor, we could move in quite close to them:

The other type of sharks we saw were reef sharks:

There were lobsters:

And turtles. I’m not 100% sure, but I thin this is a green sea turtle (Chelonia mydas):

There were rays of wildly varying size. This was a larger one:

And there were these almost entirely white fish whose name I don’t know:

45 million red crabs migrate to the sea

November 8, 2024 • 12:30 pm

To end, the week, we have some stunning videos from BBC Earth and other places, depicting the migratory behavior of the red crabs of Christmas Island, a small Australian territory (135 km², pop. 1692 ) near Indonesia: encircled below. Their vernacular name is The Christmas Island red crab, the Latin binomial is Gecarcoidea natalis, and they are  endemic to that island and the Cocos (Keeling) Islands in the Indian Ocean.

TUBS, CC BY-SA 3.0, via Wikimedia Commons

The life cycle of this crustacean is described here, but the videos are more impressive. Here are the basic facts:

The migration starts with the first rainfall of the wet season. This is usually in October or November, but can sometimes be as late as December or January.

Red crabs all over the island leave their homes at the same time and start marching towards the ocean to mate and spawn. Male crabs lead the migration and are joined by females along the way.

The exact timing and speed of the migration is determined by the phase of the moon. Red crabs always spawn before dawn on a receding high-tide during the last quarter of the moon. Incredibly, they know exactly when to leave their burrows to make this lunar date.

However, because crabs wait until the first rainfall to start their trek, they sometimes have to hurry. If the rains arrive close to the optimal spawning date, they will move rapidly. But if the rain comes early they may take their time, stopping to eat and drink on their way to the coast.

If it begins raining too late to make the spawning date, some crabs will stay in their burrows and migrate the following month instead.

And from BBC Earth, narrated by Attenborough. Note that the crabs breathe through gills, which must be kept moist. They live on land, but in moist habitats, but a remnant of their evolutionary origin is their need to go back to the ocean to spawn. Note that they walk sideways.

Note that they mate during the migration, too, so it’s not just females who are drawn to the sea at this time. A similar video, but also showing one of their predators and some of the other dangers they face.

I especially like this video because it shows how the island’s human inhabitants care for and protect the crabs: