Category: molluscs

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.

A Dumbo octopus

June 17, 2023 • 2:19 pm

There are 17 species in the genus Grimpoteuthis, or “Dumbo octopus”, and you can see where the name comes from in the short video below. It was just posted a few days ago (this species is in the deep ocean), and here are the YouTube notes:

Our Corps of Exploration spotted this absolutely adorable pale orange dumbo octopus surrounded by marine snow around 1,400 meters deep while diving on the summit of “Guyot 10” in the waters of the Pacific Remote Islands. Don’t let its Disney-like appearance fool you; these octopuses (Grimpoteuthis spp) are actually predators! They propel themselves through the water using those famous ear-shaped fins to find food, then gobble their prey up whole, feasting on a plethora of deep sea critters such as copepods, isopods, bristle worms, and amphipods. Learn more about this expedition funded by NOAA Ocean Exploration via the Ocean Exploration Cooperative Institute: https://nautiluslive.org/cruise/na149

And from Wikipedia:

The name “dumbo” originates from their resemblance to the title character of Disney‘s 1941 film Dumbo, having a prominent ear-like fin which extends from the mantle above each eye. There are 17 species recognized in the genus. Prey include crustaceans, bivalves, worms and copepods. The average life span of various Grimpoteuthis species is 3 to 5 years.

Here’s a shot of Dumbo (who could fly with his ears) from the original movie, and I’ve put the trailer below it”

From IMDb

Remember this?

 

Readers’ wildlife photos

May 31, 2023 • 8:15 am

Thanks to all who sent in photos; we’re good for a short while, but please don’t forget the site!

It’s been a while since we’ve heard from Tony Eales, who recently moved to Canberra, but he sent us a diverse batch of photos. His narrative is indented, and you can enlarge the photos by clicking on them.

So, we had a long weekend for Reconciliation Day and despite it being bitterly cold, the wife and I decided to go camping. We went to the Southern Forest National Park, three hours away, because in my investigations these are the temperate rainforests closest to my new home in Canberra.

This area was also ground zero for some of the worst of the unprecedented 2019-2020 bushfire season, and the damage to giant swathes of forest was still in evidence. Where we camped was completely destroyed in those bushfires and while the rainforest plants were back along the streams, the same could not be said for the canopy, and most of the understory was a mix of packed wattle and invasive fireweed. Very different to the sparser and fern-heavy understory that would have existed before the fires.

But despite the cold and the damage there was a lot of life around to be seen and heard. I heard Superb Lyrebirds calling every day and briefly saw one dash into the understory from the side of the road as I was driving past.

Other birds were more friendly like this beautiful Scarlet Robin (Petroica boodang). The Austro-Papuan Robins are not closely related to northern hemisphere robins but they come in a variety of shades of red, orange, pink, yellow and white:

In the mountains closer to Canberra, I saw Flame Robins (Petroica phoenicea), close cousins of the Scarlet Robins:

There were also flocks of the tiny Brown Thornbills (Acanthiza pusilla) foraging through the leaves for small insects:

We saw many signs of wombats but no actual wombats themselves but there were plenty of Swamp Wallabies (Wallabia bicolor) around:

At night, in among the leaves I found more than enough invertebrates to keep me photographing for a couple of hours each evening.
There was the impressive Badge Huntsman (Neosparassus cf diana):

Lots of Snowy Mountain Humpbacked Slugs (Cystopelta astra):

Several large ant species out hunting including this impressive Inchman Bulldog Ant (Myrmecia forficata):

And on the way home we stopped at Black Lake and photographed a couple of duck species that are new to me because they are more common in Southern Australia. Unfortunately, I am much more set up for close up photography than distance photography.

The Australian Shelduck (Tadorna tadornoides):

and Australasian Shovelers (Spatula rhynchotis):

Readers’ wildlife photos

May 11, 2023 • 8:15 am

Today’s photos come from Israel and the camera of Scott Goeppner, a postdoctoral researcher at the Blaustein Institutes for Desert Research (BIDR), Mitrani Department of Desert Ecology. His narrative and captions are indented, and you can enlarge his photos by clicking on them.

Here are some pictures from around the town of Midreshet Ben-Gurion, which is located in the Negev desert of southern Israel:

First, a Nubian Ibex (Capra nubiana), which are common in the town. This one was taken by the cliffs on the southern edge of the town. Ibex are excellent climbers and they like to hang out on the cliffs which provide safety from predators.

Next, the gravesite of David Ben-Gurion, the first prime minister of Israel and the namesake of Ben-Gurion University. Ben-Gurion led efforts to settle the Negev desert, and moved to Sde Boker, just north of Midreshet Ben-Gurion, after his retirement. He is buried with his wife Paula at the edge of a cliff overlooking the Zin valley.

Behind Ben-Gurion’s grave is a lush park, where the ibex also like to spend time. Here are some more ibex in the park:

Next, a panorama of the desert:

Next, some invertebrates from the area, including:

A Mediterranean red bug (Scantius aegyptius):

A harvestman (Order Opiliones, species unknown):

A cool beetle (Sepidium tricuspidatum):

A terrestrial snail (I’m not sure of the species). The Negev desert does not get much rain, but it does get a fair amount of dew. The dew is enough to support the growth of lichen and algae which the snails pop out and eat during the rainy season:

And a scorpion (Buthus israelis). Probably would not be pleasant to be stung by this!:

Next, some photos from Ein Avdat, an oasis with permanent spring fed pools about 2.5 miles from town.

The waterfall in Ein Avdat:

An Atlantic Terebinth tree (Pistacia atlantica):

On December 25th and 26th, there was an intense rainstorm over the desert that temporarily refilled many of the dry riverbeds near the town. Here is a photo of one of the waterfalls that formed as a result:

ZeFrank on predatory mussels and their mimicry

March 23, 2023 • 1:30 pm

This is one of my all-time favorite examples of the power of natural selection, and one I taught in my evolution class as an example of mimicry. These freshwater mussels have a load of fertilized eggs that produce larvae that feed on fish blood until they’re grown. This poses a problem: how do you get the larvae into the fish mouth, where they can latch onto the fish tissue and feed on blood in the vascularized gills?

This video shows several ways. The first is simple: the mussel latches onto a fish and then forces the larvae into the trapped fish’s mouth, the prime feeding spot for larvae (gills are loaded with blood vessels to absorb oxygen from the water). The larvae develop for a while and then drop off the fish to grow into sedentary adult mussels. This means that the mussels have to let the now-parasitized fish go so they can disperse the young.

The other way—the really amazing way—is found in Lampsilis mussels, who have evolved a brood pouch, containing the larvae, on the edge of the mantle. The brood pouch looks remarkably like a fish, and so a predatory fish approaches to nibble on the pouch. At that moment, the mussel squirts the larvae into the predator’s mouth, where they fasten onto its gills. Instead of getting a meal, the predatory fish becomes a meal, but not one that’s fatal to the fish. Still other mussels release larvae that look like worms or fly pupae and, when gobbled by hungry fish, again latch onto the fish’s blood vessels.  Still other mussels put out lures that look like fish and act like the brood pouch, squirting mussel larvae into the mouths of hungry fish.

What’s remarkable in all this is how closely the brood pouch—or the larvae—have evolved to look like food. Mimicry like this is a good way to show the power of natural selection!

Readers’ wildlife photos

December 29, 2022 • 8:15 am

Thanks to readers who have sent in photos. But I NEED MOAR! (Remember, it’s my birthday tomorrow.)

Today we have a new contributor with swell photos of Scotland: Taryn Overton.  Taryn’s captions and narrative are indented, and you can enlarge the photos by clicking on them. This is the first half of the batch; the rest will be posted later.

This year I spent the month of September in Scotland on a walking holiday.  We explored the Kintyre Peninsula via the Kintyre Way trail, went North to the Isles of Gigha and Skye, and ended in the Northern Highlands.  We were prepared for rain given the notorious Scotland weather, but apart from one 18 mile day in a downpour, hop skipped and jumped alongside the sun.  The superlatives ran out early on – it was a restorative trip, made all the more wonderful by the generous and witty Scottish hikers and B&B hosts that we interacted with. These 14 photos are from the Kintyre Way.

Loch Fyne, viewed on the first leg of the Kintyre Way.  Mist surrounded much of the landscape, but an occasional azure slit made it through the clouds.

Kintyre Way: Claonaig to Clachan, crossing Kintyre from East to West.  Mostly meadows with a few scattered lochs.

Arion ater (European black slug).  These terrestrial gastropods were seen frequently along the trail.

Kintyre Way: Clachan to Tayinloan.  The water was crystal clear and lapped pleasantly along the multicolored smooth blue/red/grey stones.

Sunset in Tayinloan.  Once the sun began to creep downward, we found a beach and appreciated a rare look at the sun setting over the Isles of Gigha, Islay, and Jura.  Colors eventually drifted to pastels, and we passed a small camp of driftwood with various hanging shells.

Kintyre Way: Tayinloan to Carradale.  The pinnacle of a steep climb through sodden mud was a walk through meadows of Scottish Heather to a view high above Kilbrannan Sound.

Saddell Bay – the location where Paul and Linda McCartney, along with the rest of Wings, filmed the ‘Mull of Kintyre’ music video (we of course played this on a small portable speaker we brought along for the occasion).  This is Anthony Gormley’s sculpture of an iron life-sized geometric man.  Saddell Castle is in the background.  It was built by David Hamilton, Bishop of Argyll in 1508-1512.

JAC: You can see the music video here.

Kintyre Way: Carradale to Lussa Loch.  What a trail!  Described as impassible at high tide, and treacherous when wet.  The path was stunning and over multiple moss-covered rocks and deceptive grass fields that commonly gave way to hidden pools of water.

Kintyre Way: Campbeltown to Southend.  A lovely walk, mostly along the coast.

The true Mull of Kintyre.  The North Channel and Irish Sea were a stunning deep uniform blue.  Eleven miles in the distance, we had a clear look at Ireland’s coastline.  We zigged and zagged down to the lighthouse.

Kintyre Way: Southend to Machrihanish.  The most challenging leg, but an incredible journey.  When we met fellow walkers, they would simply relay ‘aye, you’ll know you’ve done it’ when we talked about this upcoming section.  Mostly uphill in a ‘climb to the clouds’ sort of manner on wet, boggy ground.  We again had views of the Northern coast of Ireland and stood for a time simply taking in the view – the peace – the EXPANSE of blue water before us with tiny white caps sprinkled here and there.

Kintyre Way: Southend to Machrihanish.  The most treacherous/slick part of the walk.  This fall-on-your shoulder/side/face/anything trail was worth it for the incredible views.  Mountain goat country – we even saw a few in the distance.

An example of mild bog.

The Kintyre Way waymarker – blue poles visible on clear days, nearly invisible in thick fog!  We got lost several times along the trail, but eventually found our way.

Readers’ wildlife photos

December 10, 2022 • 8:15 am

Today’s batch comes from reader Bruce Cohrane, whose photos and captions are indented. Click on them to enlarge them. I’ve added a map of Seneca Lake below, one of New York’s glacial “finger lakes”:

I am fortunate enough to have inherited (along with my late sister) a cottage on Seneca Lake in the Finger Lakes region, built by my grandfather in 1939.  I first went there when I was less than one year old, and I’ve been returning yearly since then (and I’m well into my Medicare years).

First, the setting:

We are on the east side of the lake, so sunsets are often spectacular.

In addition to scenic beauty, the area is increasingly recognized as one of the outstanding wine-producing regions in America. These vines are across the road from our place:

A bit of background on the next two photos. The Seneca Army Depot was built during World War Two, and remained in operation until 2000.  It was a storage and disposal site for explosives  (including nuclear material) and thus was secured tightly.  Contained within its 10,000 acres is a deer (Odocoileus virginianus) population that contains a high frequency of leucistic (white) deer, most likely due to a combination of founder effect and subsequent genetic drift.  Note that these animals are not albinos and actually have brown eyes.

White and brown deer:

Young white deer:

The Erie Canal runs north of the lakes and, while no longer used much for commerce, is a great recreational resource.  In 2010, we rented a house boat and spent three days on the canal, including a swing through Montezuma National Wildlife Refuge, situated in the wetlands north of Cayuga Lake.  The Canal and Refuge are great places for birding.

Great Blue Heron (Ardea herodias):

Osprey (Pandion haliaetus):

Bald Eagle (Haliaeetus leucocephalus):

On our cruise, we had to pass through multiple locks, some of which were home to invasive zebra mussels (Dreissena polymorpha), a scourge of the Great Lakes area:

Returning to our cottage, we often have visitors.

Eastern Cottontail Rabbit (Sylvilagus floridanus):

Common Watersnake (Nerodia sipodon) off our dock:

Finally, when traveling between my Ohio and New York homes, I often drive through the Alleghenies in Western Pennsylvania.  The town of Benezette, in Elk County, is at the heart of the range of a herd of 1400 elk (Cervus canadensis).  While eastern elk were driven to extinction in the 1800’s, they were reintroduced to Pennsylvania (from Yellowstone) in 1912, and despite poaching and farmers’ wrath, have persisted until the present.  Viewing is best in the breeding season (September and October).

Female:

Male: