Category: crustaceans

ZeFrank has crabs!

October 30, 2023 • 1:30 pm

Reader Mary sent me a video by the incomparable ZeFrank, and it’s a lovely one, a full 15 minutes about crabs with lots of great video and accurate biology. Mary said this:

Really good one with lots of interesting evolutionary implications!

There’s all kind of cool stuff about coconut crabs, the famous migrating red crabs of Christmas Island, hermit crabs, sponge crabs, decorator crabs, boxer crabs (don’t miss these!), spider crabs, fiddler crabs  And yes, there’s evolution: straight adaptation in morphology and behavior by natural selection, sexual selection, and evolutionary tradeoffs.

(There’s an ad from 2:45 until 3:35.)

h/t: Tim

Mantis shrimp dismantles clam

July 28, 2023 • 2:00 pm

It’s Friday afternoon, the ducks are fed and watered for the weekend (it’s hot today but will cool down) and I’m soon off to hear about the fate of Botany Pond. This all means that it’s time for ani animal video.

How does it do this?  See the next video, which shows that the shrimp actually packs a double punch, with the second involving boiling water.

The explanation from Wikipedia:

Mantis shrimp are commonly separated into many (most fall into spears and smashers but there are some outliers)[9] distinct groups determined by the type of claws they possess:

  • Smashers possess a much more developed club and a more rudimentary spear (which is nevertheless quite sharp and still used in fights between their own kind); the club is used to bludgeon and smash their meals apart. The inner aspect of the terminal portion of the appendage can also possess a sharp edge, used to cut prey while the mantis shrimp swims.
  • Spearers are armed with spiny appendages – the spines having barbed tips – used to stab and snag prey.

Both types strike by rapidly unfolding and swinging their raptorial claws at the prey, and can inflict serious damage on victims significantly greater in size than themselves. In smashers, these two weapons are employed with blinding quickness, with an acceleration of 10,400 g (102,000 m/s2 or 335,000 ft/s2) and speeds of 23 m/s (83 km/h; 51 mph) from a standing start.[10] Because they strike so rapidly, they generate vapor-filled bubbles in the water between the appendage and the striking surface—known as cavitation bubbles.[10] The collapse of these cavitation bubbles produces measurable forces on their prey in addition to the instantaneous forces of 1,500 newtons that are caused by the impact of the appendage against the striking surface, which means that the prey is hit twice by a single strike; first by the claw and then by the collapsing cavitation bubbles that immediately follow.[11] Even if the initial strike misses the prey, the resulting shock wave can be enough to stun or kill.

Smashers use this ability to attack crabs, snails, rock oysters, and other molluscs, their blunt clubs enabling them to crack the shells of their prey into pieces. Spearers, however, prefer the meat of softer animals, such as fish, which their barbed claws can more easily slice and snag.

Readers’ wildlife photos

July 20, 2023 • 8:15 am

Today’s photos of Costa Rica come from reader Leo Glenn. His narrative is indented, and you can enlarge the photos by clicking on them:

Here are some photos from my recent trip to Costa Rica. We spent most of our time on the Pacific side in the northwest region, in Guanacaste Province. The Pacific side has more distinct dry and rainy seasons, in contrast with the Caribbean side, which receives considerably more rainfall year round. Although slightly smaller in land area than the U.S. state of West Virginia, Costa Rica boasts 32 national parks, over 50 wildlife refuges, and over a dozen forest and biological reserves. This creates tension, of course, between preservation efforts and ecotourism, which is the country’s largest source of income.

The view from a higher elevation, about 20 minutes from where we stayed.

The local beach, Playa Avellanas, was a short walk from our lodging via a boardwalk that traversed a mangrove swamp, comprised mostly of White Mangrove (Laguncularia racemosa). After an earthquake in 2012, the land along the coast rose one meter, which closed off the mouth of the river, causing the water in the mangrove swamp to stagnate and kill all of the trees (thus the many dead trees in the foreground). A restoration effort was undertaken to restore the area and replant the mangroves. It appears to have been largely successful, though it will be years before the new trees mature and the ecosystem returns to something close to its pre-earthquake state.

The shallow and drier areas of the swamp were populated by several crab species, including the Racer Mangrove Crab (Goniopsis pulchra).

 

The forested areas on the path to the beach were dotted with numerous small burrows,  inhabited by Red Land Crabs (Gecarcinus quadratus), which would freeze when approached, before slowly slinking backwards into their holes.

 A juvenile Atlantic Ghost Crab (Ocypode quadrata). They were lightning fast, and very hard to photograph.

Some Brown Pelicans (Pelecanus occidentalis), flying over the beach. There were quite a few more in the line. Apparently, a group of pelicans can be called a pod, a pouch, a scoop, a squadron, or, if fishing as a group, a fleet.

Although colorful butterflies were abundant, I lacked the skill, patience, and hardware to photograph them, unless, as in this instance, I got lucky when one happened to land in the swimming pool. We rescued it immediately, of course, and after a few minutes spent drying its wings, it took flight. Theona Checkerspot (Chlosyne theona).

I did manage one halfway decent photo of an Apricot Sulphur (Phoebis argante).

A Crested Caracara (Caracara plancus), described on Wikipedia as “a bold, opportunistic raptor, often seen walking around on the ground looking for food,” which is exactly what this one was doing.

A nest of Northern Warrior Wasps (Synoeca septentrionalis), in a tree outside our lodging. According to Wikipedia, “It is a swarm-founding wasp that is also eusocial, exhibiting complicated nest structure and defense mechanisms.” The nest was about 30 ft up in the tree, and without a telephoto lens (or a very long stepladder), this was the best photo I could get. Its high location in the tree was a comfort to us, being so close to our rental house. Though not a particularly aggressive species, they are reported to have a very painful sting.

Readers’ wildlife photos

July 17, 2023 • 8:15 am

Today’s photos come from evolutionist Jody Hey from Temple University. His narrative and captions are indented, and you can click on the photos to enlarge them.

The coast of Maine offers a lot of beautiful scenery and some great wildlife watching. My visits there are usually in mid-summer,  which if you are inland is not the best time of year for watching birds. However,  the seaside has lots of visible action year round.  On or near the coast, many of the birds are large, and the sightlines have few obstructions, so getting passable photographs can be relatively easy.  Below are some pictures taken at Marshall Point, the location of a much photographed lighthouse near Port Clyde, and the island of Monhegan,  home to a small community of lobstering folk and artists, and just a  12 mile ferry ride from Port Clyde.

Marshall Pt is a public park and makes a popular and idyllic picnic  spot when the weather is good.    This photo shows the Marshall Pt lighthouse at high tide.  Many will recognize it, as it was famously the eastern terminus for one of Forest Gump’s cross-country runs.

One day I had just finished my picnic lunch and was walking on the beach facing the harbor of Port Clyde, and saw this Great Black-backed gull (Larus marinus) enjoying its own lunch, an Atlantic rock crab (Cancer irroratus).

The tidal range is quite large in coastal Maine, especially further north and east, so the things to see vary widely throughout the day.  Here is a Least sandpiper (Calidris minutilla) exploring the barnacles at low tide.

Marshall point is separated from ocean waters only by a few islands, unlike much of the jagged cost of Maine most of which is some distance from the open ocean.  This means that Common Eiders (Somateria mollissima) can be seen there year round.   In the summer their markings are fairly dull,  but in the winter and spring,  they are spectacular.

The ferry ride from Port Clyde to Monhegan offers some great opportunities to see marine mammals,  including a couple varieties of seals and Harbor Porpoises (Phocoena phocoena):

Monhegan island itself is less than 5 square miles in area,  however the majority of it is owned and maintained as wild land by a private non-profit land trust.  Visitors are free to explore the beautiful woods and rocky cliffs that dominate the eastern side of the island, as well as eat and shop in the little village.  The cliffs also offer great viewing of a variety of coastal and ocean-going birdlife.

Northern Gannets can often be seen from the cliffs  (as well as from the ferry).  Here is a somewhat blurry adult,  and a more in-focus juvenile:

This Double-crested Cormorant (Nannopterum auritus) obligingly flew directly below me at the same time as the waves were crashing:

The cliffs are also a popular nesting site for Herring Gulls (Larus argentatus):

These Cedar waxwings (Bombycilla cedrorum) were also at the Monhegan clifftops one day,  though the coastal location was fortuitous as they are a widespread and common species:

And closely things out for Monhegan,  I go this lucky shot of a Common Raven (Corvus corax) one day, deep in the spruce woods:

Lastly,  a lagniappe  (as Jerry would say).  Not far from Monhegan and Marshall Point is Eastern Egg Rock,  home to the world’s first restored colony of Atlantic Puffins (Fratercula arctica).  The story of that restoration is fascinating,  and now it is apparently safe for the birds to be seen by tourists during the breeding season (from a boat, that is).  I took the boat tour one day a couple years ago,  just before the end of the season when there were only a few puffins to be seen,  but at least I got a picture:

Spot the hermit crab!

July 10, 2023 • 9:00 am

Reader Leo Glenn sends a “spot the hermit crab” photo with these notes:

 I’m sending you a Spot the Hermit Crab photo, taken at Playa Avellanas, Guancacaste Province, Costa Rica. I believe it is an Ecuadorian Hermit Crab (Coenobita compressus). I would rate it as “difficult”, and for readers who want a formidable challenge.

Click to enlarge, of course, and look carefully. Please do not tell people where it is when you comment; just say, “I found it” (if you did!)

The reveal will be up at noon Chicago time.

 

Readers’ wildlife photos

January 4, 2023 • 8:15 am

Send in your photos. In an ideal steady state, I’d get one batch per day, but that’s not coming. Thanks!

Today’s batch, centered on Arkansas waterfalls, comes from reader Kevin Elskin. His notes and IDs are indented, and you can enlarge his photos by clicking on them.

Recently a contributor sent photos from the Kintyre Peninsula of Scotland. That brought back memories from a recent trip, and I wanted to add one photo of my own. At the very southern end of Kintyre lay a quaint golf course called Dunaverty. If this course were located in the middle of Iowa then no one would give it a second thought. But located on the ocean on the Mull of Kintyre, it rivals Pebble Beach for the views (and at a fraction of the cost). That is Ireland in the distance, over the ocean, off to the left.

But on to my main event, a short tour of some Arkansas waterfalls. I wish to assure you that I do not work for the Arkansas Department of Tourism, but when things are shut down you tour close to home.

You might be thinking, “Arkansas has waterfalls?”, but yes we do. In fact there is a book by Tim Ernst called Arkansas Waterfalls that documents over 200 different waterfalls. They are not spectacular falls like Niagara or Yosemite, but the sound of falling water, up close, is a tonic for the soul, a meditation that drowns out the noise our talented ape brains generate in such volume. If you that experience with a healthy hike through the woods, and let us say that your mind and body will thank you for the effort.

Arkansas waterfalls are temperamental. They come and go with the rains. This means the best waterfall days are days when the ground is wet and muddy, perhaps after weeks of spring rains or the hours just after a “gully washer” or “toad strangler” of a thunderstorm. Waterfalls in Arkansas come in many varieties. Some can be seen from the comfort of your car. Others might require a moderate hike down a clearly marked trail. The most fun are the ones that require significant bushwacking through the hills, with careful climbs down steep cliffs into deeply shadowed hollows.  Your reward will be solitude, as few tend to venture there. And maybe a few ticks, so check yourself often.

With that preamble, let me begin with photos of Arkansas’ tallest waterfall, Hemmed-in-Hollow. At 209 feet high, this waterfall claims to be the tallest between the Appalachians and the Rockies. If you are canoeing on the Buffalo River, this fall is only a short hike from the river. We hiked in from the other direction, which involves a 1000 foot elevation change. Getting in was easy, getting out was a haul.

The first photo shows the falls from a distance as we were hiking in.

The second photo is from the base of the falls. For perspective, there are people in the shadows at the bottom of the photo.

The third photo was taken after a small climb up from the base. My nephew is visible in the photo.

Another fun waterfall that is a moderate but easy hike is call Glory Hole. Fourth grade jokes aside, the neat thing about Glory Hole is that water falls through a hole in the outcropped rock.

A fierce guardian we found near the falls:

And wherever you look, there is a pleasant cascade of water running to greet you.

Falling Water Falls can literally be viewed from the front seat of your car. It is not terribly high, but we managed to catch it on a very high flow day after heavy rains. A black and white and a color enhanced higher definition photo for your pleasure.

Last winter, my son and my brother hiked to Magnolia Falls. Again not overly impressive, but just a lovely spot to enjoy a cool winter day. You can see my son next to the falls in the second photo.

New Year’s Day 2022 I took a solo jaunt and visited Glory B falls. Another falls that can be viewed from your car. Or if you hike down you can see it from both sides.

And again, on a rainy day, there are many unnamed adjacent falls for your pleasure.

So come visit Arkansas sometime. Yeah, it is full of redneck Trump supporters. But it has its charms, too.