Readers’ wildlife photos

November 22, 2022 • 8:15 am

We’re running low on photos, folks, so if you have some good ones, you know what to do. .

Today’s batch comes from Brian Cox, an instructor at Assinboine Community College in Manitoba (see his earlier photos here). Brian’s notes and IDs are indented, and you can enlarge the photos by clicking on them.

A crayfish claw jammed between dock boards in Kenora, Ontario, Canada. I don’t know the species of crayfish, but here are some possibilities.

Stilt sandpiper (Calidris himantopus) in my hometown of Brandon, Manitoba.

A neighbour threw his Christmas tree on a bonfire. I was able to capture the vibrant colours, but I can only guess at the tree species. Is it a white or black spruce? Perhaps a jack pine?

Capturing a red-tailed hawk (Buteo jamaicensis) in flight with a manual-focus zoom lens can sometimes come down to luck. My city is surrounded by farmer’s fields, prime hunting grounds from these hawks.

This red-tailed hawk was happily stripping pieces off a Northern pocket gopher (Thomomys talpoides) until I got too close. The image is a little out of focus…

And this gopher completely objects to the hawk’s lunch preferences.

I startled this North American porcupine (Erethizon dorsatum), but waited for it to find the right safety-tree to climb up. I think it gave me a little smile.

Riding Mountain National Park is a one-hour drive from my home. There are approximately 1000 American black bears (Ursus americanus) in a 2,969 km2 (1,146 sq mi) area. This one was enjoying fresh dandelions (Taraxacum officinale).

Readers’ wildlife photos

September 23, 2022 • 8:00 am

Today’s photos come from reader Christopher McLaughlin, whose notes are indented. You can enlarge his photos by clicking on them.

I’ll offer up this handful of wildflower/landscape photos, hopefully they are of interest. I don’t have fancy equipment, just an iPhone 11.  They were taken last summer, July 17, 2021, in between storms at Jerry Smith Park (supposedly a remnant prairie) in south Kansas City.

Silphium laciniatum [Prairie Compass Plant]:

Silphium laciniatum, Liatris pycnostachya [Prarie Blazing Star],and  Echinacea pallida, [Pale Purple Coneflower]:

Silphium integrifolium [rosinweed]:

I am not certain on the species, or even the genus of this crayfish, possibly Orconectes virilis, the rather common Northern Crayfish. This was taken on a rainy spring morning at Gama Grass Conservation Area, Vernon county MO.

Otherwise not an exciting find, as crayfish are quite common, but finding her loaded with babies was a treat. Pardon the dirty hands and fingernails.

Silphium perfoliatum [cup plant]from my back yard. Silphium being my favorite genus, I have four of the five species that grow in Missouri in my yard, with seeds of the fifth species on the way. They are excellent for attracting pollinators, including hummingbirds, and the seeds are eaten by several birds.

Guardian retracts claim that Cornwall is infested with “venomous crabs”

August 8, 2022 • 11:15 am

Yesterday morning, thanks to Matthew, I pointed out that the Guardian had screwed up one of its biology stories, the one noted in this headline:

What apparently had happened is that somebody at a news service (see below) googled “crab spider” instead of “spider crab”, and concluded that spider crabs were venomous. Then the Guardian simply cut and pasted the false assertions about the spider crab—no crabs are venomous though some are toxic to eat—to create a clickbait story.

Pity, pity, because since the crabs aren’t venomous, the story loses a lot of its click-y allure.  A number of people pointed out to the Guardian that this story wasn’t exactly true (the swarming part was). Matthew also informed one of his friends who works at the Guardian (see below). Regardless, the complaints worked, and now there’s a new story sans venomous crabs. Click below to see the latest story, lacking the word “venomous”.

And kudos to the Guardian for noting that they changed the story. At the bottom of the new page you can read this:

 This article was amended on 8 August 2022. An earlier version incorrectly stated in the headline and text that the spider crabs massing at Cornish beaches were “venomous”; no species of crab is venomous. Also, their Latin species name is Maja brachydactyla, not “Hyas araneus” as we said.

Someone else must have corrected the species name. I took the paper at its word, for Hyas araneus is the “great spider crab”. Now we learn that these un-venomous crabs are actually Maja brachydactyla, in a completely different family. Now how did they screw that one up?  By copying from another source?

Well, all’s well that ends well, except, perhaps, for the would-be bathers who avoided the waters off Cornwall.

*********

Here’s Matthew’s email to the Guardian:

From: Matthew Cobb

Subject: Crab spiders

Date: 7 August 2022 at 22:11:22 BST

To: guardian.letters@guardian.co.uk” <guardian.letters@guardian.co.uk>

Over the weekend The Guardian website followed the rest of the UK press by printing a story about ‘venomous spider crabs’ moving into shallow waters off Cornwall to moult [https://www.theguardian.com/environment/2022/aug/06/spider-crabs-swarm-in-shallow-waters-on-cornish-beach].

Virtually all of these stories – including that in the Guardian –  claimed the crabs ‘have a venomous bite that is poisonous to their prey but harmless to humans’.

This is not true. No crab is venomous. Indeed, out of over 7.000 species of crustacean, only one is known to be venomous, and it is not a crab.

This error – which the Guardian has still not uncorrected, despite repeated alerts on social media – appears to have originated in some journalist googling ‘spider crab’  and not noticing that the pages they got back referred to ‘crab spider’. It was then simply copied by other journalists, including your own.

It is hard to know which is more disheartening: the original error, or your thoughtless repeating of it. This example does not particularly matter, but confidence in the press is a fragile thing.

Matthew Cobb

The Guardian responded by saying that the false claims about venom and species name were provided by a news agency based in south-west England, and noted that they’d changed the text and added a footnote. 

The Guardian screws up a science article

August 7, 2022 • 7:30 am

After Matthew corrected this story via Twitter, it’s still up prominently on the Guardian website (at least as of 6:30 this morning Chicago time).  Click to read:

The relevant bit from the story is this:

Thousands of venomous crabs converged on the beaches of Cornwall due to rising sea temperatures caused by the climate crisis. The migratory creatures swarmed in the shallow water in St Ives, shedding their shells before returning to depths of up to 300ft.

The crustaceans are instantly recognisable for their long legs and pincers and have a venomous bite that is poisonous to their prey but harmless to humans.

Oy! What clickbait: guaranteed to drive the swimmers out of the Cornwall seas! And it did!

Their presence at Porthgwidden Beach was enough to put many bathers off entering the sea.

However, Kate Lowe, a marine photographer captured the event just days after a snorkeler was bitten by a blue shark during an excursion off Penzance.

 

Remember, this has happened “just days after a snorkeler was bitten by a blue shark” – like that has anything to do with anything except alarming people!

Furthermore, it’s wrong: this species, Hyas araneus, the giant spider crab, is not venomous. As far as I know, while some crabs are poisonous (their bodies contain toxins that could kill you), no crabs are venomous, i.e., injecting venom into their prey.

These crabs are innocuous unless they nip you.  But how did the Guardian get it wrong?  Matthew explains:

The article is about spider crabs, which are indeed crabs. They are coming into shallow, warm waters in Cornwall to moult together. About two days ago, the tabloids here had the story, and said these crabs were venomous but this was harmless to humans. The Guardian freelancer  basically cut and pasted the story, including this phrase, which comes from a Google hit for “crab spider” (which is a spider, and is obviously venomous). They also headlined it “Venomous visitors”. There is only one known venomous crustacean, it is a remipedian (more closely related to a fly than to a crab).

Matthew even tweeted to the Guardian to get them to correct this (we petulant biologists dislike these errors, especially if they can panic the public):

This was over four hours ago, and the headline stays. (I also tweeted them.) As Matthew emailed me:

They won’t chnage it… Any more than any of the tabloids did. Google this
are spider crabs venomous
And you get about a dozen identical articles – from all the leading UK media – with the same crap cut and pasted…
Come on, Guardian, get someone who knows to vet your science articles!

Animal pollination of a seaweed

July 30, 2022 • 11:15 am

This is the first known case of an animal fertilizing seaweed, and was deemed significant enough to be published in Science. Click on the screenshot to see it; the pdf is here, and the full reference at the bottom.

There was one case reported previously; as the authors note, “foraging marine invertebrates were shown to carry and transfer pollen grains from male to female flowers in the seagrass Thalassia testudinum K. D. Koenig.” The pollinators were crustaceans, as they are in this case, and today’s results were apparently deemed Science-worthy because they involve seaweeds, long thought to have been fertilized only by water currents, and because the authors not only did experiments supporting fertilization by isopod crustaceans, but also showed that  male gametes of the seaweed are affixed to the body of the isopods.

The players are the marine isopod Idotea balthica, and the seaweed is the red alga Gracilaria gracilis. Here they are:

The fertilizer, I. balthica:

The fertilizee, G. gracilis, which grows in a bushlike fashion:

The isopod crustacean is often found tightly affixed to the seaweed, eating epiphytes that cover it, and the isopod gets food. The authors suggest that this association is a mutualism, perhaps evolved:

Although I. balthica grazes on other seaweed, it does not feed directly on Gracilaria but rather eliminates epiphytes at the surface of the thallus while protecting itself from predators. We suggest that the relationship could be mutually beneficial. For I. balthica, the seaweed provides shelter, and epiphytic diatoms found adhering to the surface of the thallus, whose frustules (or thecae) are found in the feces of idoteas, appear to be an important food source. In return, G. gracilis benefits through increased growth rate owing to reduced fouling and improved reproductive success.

The seaweed is dioecious, meaning that entire plants are either male or female. This poses the problem of getting the male gametes, which are immotile cells called spermatia, to the female receptive structure, called the trichogyne. Water flow is an inefficient way to do this, especially if opposite-sex plants are far apart and the spermatia don’t live that long. But Isopods can help by moving between the plants.

Fertilization, by the way, occurs when spermatia encounter the trichogyne, forming a diploid structure on the female plant called a cystocarp. If you see one, you know that the female has been fertilized. Below a cystocarp with the caption, both taken from the paper’s supplementary materials. The cystocarp itself produces spores that are released into the environment, and these undergo a complex life cycle including meiosis, so that the resulting seaweed plants are actually haploid, having only one set of chromosomes. Red algae have remarkably complex life cycles (see here).

Male isopods of the species noted above are often found gripping the male reproductive structures of red algae, and here’s where they pick up the spermatia from the male (in the photo below, the scale bar is 1 mm long:

The authors did two tests to see if isopods effect fertilization between male and female seaweeds, and also inspected the isopods to see if they actually carried spermatia. All the data show that yes, the isopods are pollinators. The experiments are simple.

Experiment 1: Virgin female algae were placed in saltwater aquaria along with males producing spermatia. There were also isopods, as well as a control with the two sexes of algae but with no isopods. Fertilization of the females was then measured.

A diagram of the experiment:  “A” is the experimental setup with isopods, “B” the isopod-less control

Fertilization success was measured by the number of cystocarps per centimeter of stem. As the data show, fertilization was 20 times higher when isopods were around than when they weren’t. The small sample size resulted in pretty big error bars, but the result is a statistically significant difference, though not “highly” significant.

Experiment 2: Virgin female seaweed plants were placed in saltwater aquaria along with isopods that had either contacted reproductive male thalli along with a control that had been handled identically but without isopods.  Fertilization ws then measured. I show the design and then the results, which were also significant, though fertilization was far less effective—perhaps because in the experiment above the isopods could go back and forth repeatedly between males and females.

A significant difference: more fertilization when isopods were there:

 

Finally, the authors examined the isopods themselves that had been associated with the male seaweeds, using staining and confocal laser scanning microscopy. You can see the spermatia (stained green dots) adhering to the crustaceans in the photos below:

There are a lot of them, and they tend to stick to the junctions between body segments of the isopod.

The upshot: In the laboratory, there’s no doubt that isopods can act as “pollinators” of this species of seaweed, and we can see the male gametes attached to the isopod’s body. Since this was all done in the lab, it would be nice to have confirmatory evidence in the wild.  It would be easy to capture male isopods on either male or female seaweed and determine if they, too, carry the male gametes. Experiments in the wild would be harder; you can think of some yourselves.

And, of course, given the inefficiency of fertilization in seaweeds, which when dioecious depend on water currents to get male gametes to distant female reproductive structures—a wasteful and inefficient process. Perhaps there is far more pollination of marine plants by animals than we’ve ever suspected. Right now, we know of only two cases, but that’s because experiments like these are hard to do, and perhaps because researchers hadn’t considered the possibility of animal pollination.

h/t: Athayde

____________________

Reference:   Lavaut, E. et al. 2022. Pollinators of the sea: A discovery of animal-mediated fertilization in seaweed. Science 377:528-530

Readers’ wildlife photos

January 1, 2022 • 8:30 am

This is the second part of a two-part batch of photos by Matt Young (part 1 is here). His IDs and captions are indented, and you can click on the photos to enlarge them.

I was in the Galápagos Islands during the end of December 2005, and the beginning of January 2006, bearing my trusty Canon PowerShot S30, with 3 megapixels and a 3X zoom. I took one or two pictures through an 8X monocular, but other than that I was on my own.

Mammals. The only mammals I saw, other than bipedal, were Galápagos sea lions, Zalophus wollebaeki.

A little snack:

And a nap:

Some geological features. Landscapes.

Lava tunnel. You could have easily crawled inside.

Lava flow.

Impurity.

Stubborn little plant.

Invertebrates. Sally Lightfoot crabs, Grapsus grapsus.

Painted locust, Schistocerca melanocera.

Tourist. Not exactly an invertebrate, but looking kind of spineless at the end of a hot day.

And for good measure, Machu Picchu.

Readers’ wildlife photos

November 25, 2021 • 8:00 am

Today I’ll show my own “wildlife” photos just for fun, but keep sending yours in.  Click the pictures below to enlarge them.

Feeding wild cats at a nunnery in Mystras, Greece, 2002. I always carry a box of dry cat food in my backpack in places like this.

A rare bloom in Death Valley, California, 2005. I don’t know what the moth is, and I’m baffled about where the many pollinating insects come from in those very occasional wet years. They just appear from out of nowhere.

Me feeding a grape (with permission) to a ring-tailed lemur (Lemur catta) at the Duke Lemur Center, 2006. Note the baby clinging to its belly.

Another ringtail with child:

Sifakas (lemurs, Propithecus sp.):

Cepea nemoralis snails on a fencepost, Dorset, England, 2006. The riot of colors and banding in this species was subject to a lot of investigation when I was in college, but evolutionary geneticists still don’t have an explanation for why the variation persists:

A butterfly (I don’t know the species) in the garden at Thomas Hardy’s boyhood home, 2006:

Snail and fly near Clouds Hill (T. E. Lawrence’s cottage), Wareham, Dorset, 2006:

Gooseneck barnacle, a rare and expensive delicacy. Galicia, Spain, 2006:

The one above was found on the rocks at low tide. Here are some for sale in the market. You eat the meat underneath the leather skin. It’s very good.

Me feeding a Texas longhorn on David Hillis’s and Jim Bull’s Double Helix ranch outside Austin, 2007:

Groundhog (Marmota monax), Capitol grounds, Ottawa, Canada, 2007:

Greg Mayer’s pet common snapping turtle (Chelydra serpentina); I believe its name was “Snappy”), Kenosha, Wisconsin, 2008:

Butterfly and orchids (species unknown), Guatemala, 2009:

Statue dedicated to all the lab cats “sacrificed” in medical research. St. Petersburg, 2011:

Gulls, Lake Geneva, Switzerland, 2011

Trees in autumn, Switzerland 2011:

I have many more, and perhaps I’ll post some of them on another holiday (Chanukah, Christmas, and Coynezaa are coming up).

Readers’ wildlife photos

October 16, 2021 • 8:00 am

Today we have a series of photos of ghost crabs from reader Jim McCormac, who has a blog and a “massive photo website“.  His captions are indented, and you can click on the photos to enlarge them. Do note the amazing camouflage of young crabs shown in the final photo.

Here’s something a bit different: Ghost crabs!

A common but always interesting sight along the beaches of Cape May, New Jersey – and far beyond – is the Atlantic Ghost Crab (Ocypode quadrata). They’re well named, as the crab’s sandy coloration and fleeting movements, combined with general wariness, makes them wraithlike. People new to them might wonder if they actually saw something and if so, what it was. But with minor perseverance it isn’t hard to get good looks at these fascinating decapods (ten-legs).

On a recent trip to Cape May – a birding Mecca of the East Coast – I was distracted by ghost crabs and ended up spending a fair bit of time watching and photographing them.

A crab lurks at the entrance to its burrow. They are accomplished diggers and always seem to maintain burrows to which they can retreat. Some tunnels can apparently be four feet deep. But the excavation is easy in soft beach sands and it does not take them long to mine out a new hole.

A crab in the act of construction. It uses its first two legs and the claw on that side (the claw, or cheliped, is actually part of a highly modified leg) to create a basket in which it scoops sand from the excavation.

Once the subterranean dwelling is complete, it becomes the crab’s home base. They retreat to it in the blink of an eye if threatened or disturbed. When exiting, I noticed that a crab would sometimes pause below the opening, and use its long-stalked periscope-like eyes to check the surroundings before emerging. They can rotate the eye stalks 360 degrees, increasing their efficiency at predator detection. I would imagine that gulls are one of the major threats. Great Black-backed, Herring, Laughing, and Ring-billed gulls are constantly patrolling the shoreline and would snap up a crab in a heartbeat if given a chance.

A crab dines on what appear to be the remains of another crab. They are omnivorous opportunistic scavengers, cleaning the beaches of various edible detritus. The chelipeds are used like hands, and the crabs quite dexterously handle their meals. They also will thump the claws on the sand, apparently to send signals to other crabs, and may use them as semaphores in mating rituals as do some other crabs, but I’m not sure about the latter.

There is also another use for the claws: jousting with rivals. I saw this several times, and finally got an opportunity to photograph a joust. Occasionally a foraging crab would stray far from its burrow, or venture to the sea to wet its gills. On these trips, if it would trespass too closely on another occupied burrow, the offended crab would sometimes pop out and do battle with the interloper. That’s what happened here. The guy on the left owned the burrow, and the intruder on the right was quickly vanquished after a brief locking of the horns. He sidled speedily back to his own burrow.

Atlantic Ghost Crabs take about a year to reach sexual maturity. After mating, the female deposits eggs in the ocean. The larvae develop there, and then head ashore as young crabs. I saw many juveniles on the beaches, but only because I was looking. They can be really tough to spot. The crablets are small, and their camouflage is incredible. If immobile or partially buried in the sand, they are essentially invisible. At this stage, I imagine various shorebirds – plovers, sandpipers, etc. – are major threats. The coloration and patterning of the carapace and upper legs is amazingly sand-like – a textbook example of crypsis.

After my crustacean hiatus, it was back to the business at hand: bird photography, and there was no lack of subjects there.

Readers’ wildlife photos

September 12, 2020 • 7:45 am

Please send your photos in, as to keep this feature going I need seven contributions per week. We don’t want to lose our beastie pics, right?

Today we have diverse photos from reader Dave Campbell, whose notes and IDs I’ve indented:

Here are some photos to replenish the cache with accompanying text.  I tossed in a photo with a connection to Charles Darwin and a gratuitous reference to a fictional rabbit from Brooklyn.

Eastern Spadefoot Toad (Scaphiopus holbrookii). In June, Tropical Storm Cristobal dumped five to six inches of rain on us and the following night the spadefoot toads came out.  They spend most of their lives buried underground waiting for heavy downpours.  Immediately following the rain they emerge for a few days and eat and mate and then burrow back underground to wait for the next rain.  I live on a high sandridge that is usually pretty dry so the emergence of these amphibians is a major event for us.  The adults look like little porcelain frogs with beautiful eyes.

Three weeks after the adult was photographed my property was overrun by thousands of spadefoot toadlets, sometimes as many as 20 per square meter.  21 days after the adults emerged the next generation is fully metamorphosed and hunting on dry land.  They are tiny, only about three to four millimeters long (those little white things are sand grains).  We were still seeing them three week later but the numbers decline rapidly.

Vermilion Flycatcher (Pyrocephalus obscurus).  The vermilion flycatcher is a western bird but one or two seem to take a wrong turn at Albuquerque every year and wind up in the Florida panhandle.  This male showed up at St. Mark’s National Wildlife Refuge southeast of Tallahassee, Florida last November and set up shop at the first roadside pulloff after entering the refuge marshes.  The first description of the vermilion flycatcher was made by John Gould based on a specimen collected by Charles Darwin in the Galapagos.

Tricolored Heron (Egretta tricolor)  Every spring the trees around the boardwalk over the alligator ponds at the Saint Augustine Alligator Farm become a large rookery for hundreds of nesting wading birds.  The rookery flourishes because alligators in the ponds below prevent predators like raccoons from reaching the nests.  Photographers flock to the boardwalks over the alligator ponds for a chance to capture images of the birds at very close range.  The gators get the occasional careless hatchling which bothers some of the tourists but I have never seen anyone jump off the boardwalk to effect a rescue.  This bird is reacting to the approach of its mate.

Ebony Jewelwing (Calopteryx maculata)  Photographed along a stream in the state forest near my home.  The metallic exoskeletons have structural colors that change from blue to green to blue as the angle of incidence of light changes. They are common along wooded streams.  Damselflies are my favorite insects both because they are beautiful and because they eat mosquitoes.

Brown Pelican (Pelecanus occidentalis).  Immature bird on short final for landing photographed at  Bottom Road near St. Mark’s National Wildlife Refuge in Florida.  Notice how individual flight feathers are manipulated to maximize lift in slow flight, not unlike the slats and flaps on airplanes.

Ghost Crab (Ocypode quadrata). Photographed at Long Point Park on the Florida Gulf Coast.  This young one paused at the entrance to its burrow just long enough for me to record it for posterity.

Sanderling (Calidris alba). Sanderlings are common, conspicuous, and entertaining shorebirds.  They race along the beach, following the edge of advancing and receding waves like little clockwork toys.  This bird is in fall plumage, a study in white and gray, and ignored the humans as it ran back and forth.

Paper wasp (Polistes carolina) feeding on a monarch butterfly (Danaus plexippus) larva.  Not long ago, another photographer who had submitted images wondered what happened to some of the monarch larva.  This is one likely answer.  Our first brood last spring had an adult emergence rate in the high ninety percent range.  The second brood, mostly offspring of the first one, had a success rate from first instar to adult in single digits.  The difference was at least three species of Polistes that found my milkweed patch and chowed down on larvae and two pupae.  Last fall I found bald-faced hornets (Dolichovespula maculata) feeding on monarch larvae as well.

Sequential shell swaps in hermit crabs

January 23, 2020 • 2:30 pm

Here’s another Attenborough video featuring the lifelong attempts of hermit crabs to find shells that fit them as they grow. A hermit crab without a shell is a pathetic thing (see several at 2:39), easily taken by predators or cooked by the sun. Here’s a stunning behavior in which a line of crabs forms in order of size, with the aim of each one swapping up to a bigger shell within a matter of minutes. Or course, the biggest crab needs an empty bigger shell to move into, which apparently is the case here. The picture of the lineup at 1:32 is fantastic.

The video comes from “Life Story,” part of the great BBC Earth series.