HERMIT CRABS: FLIPPING HOUSES SINCE THE JURASSIC

This little cutie is a hermit crab and he is wearing a temporary home borrowed from one of our mollusc friends. 

His body is a soft, squishy spiral that he eases into the perfect size shell time and time again as he grows. 

His first choice is always the empty shell of a marine snail but will get inventive in a pinch — nuts, wood, serpulid worm tubes, aluminium cans or wee plastic caps. 

They are inventive, polite and patient. 

You see, a hermit crabs' desire for the perfect bit of real estate will have them queueing beside larger shells — shells too large for them — to wait upon a big hermit crab to come along, discard the perfect home and slip into their new curved abode. This is all done in an orderly fashion with the hermit crabs all lined up, biggest to smallest to see who best fits the newly available shell. 

There are over 800 species of hermit crab — decapod crustaceans of the superfamily Paguroidea. Their lineage dates back to the Jurassic, 200 million years ago. Their soft squishy, weakly calcified bodies do not fossilize all that often but when they do the specimens are spectacular. Think of all the species of molluscs these lovelies have had a chance to try on — including ammonites — and all the shells that were never buried in sediment to become fossils because they were harvested as homes.  

On the shores of British Columbia, Canada, the hermit crab I come across most often is the Grainyhand hermit crab, Pagurus granosimanus. 

These wee fellows have tell-tale orange-brown antennae and olive green legs speckled with blue or white dots. 

In the Kwak̓wala language of the Kwakiutl or Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest, a shell is known as x̱ala̱'is and gugwis means house on the beach. 

I do not know the Kwak’wala word for a hermit crab, so I will think of these cuties as x̱ala̱'is gugwis — envisioning them finding the perfect sized shell on the surf worn shores of Tsax̱is, Fort Rupert, Vancouver Island. 

MIGHTY KWIKW: BALD EAGLE

Bald Eagle / Kwikw / Haliaeetus leucocephalus

A mighty Bald Eagle sitting with wings spread looks to be controlling the weather with his will as much as being subject to it. This fellow has just taken a dip for his evening meal and is drying his feathers in the wind. 

As you can imagine, waterlogged feathers make flight difficult. Their wings are built for graceful soaring and gliding on updrafts of warm air called thermals. 

Their long feathers are slotted, easily separating so air flows smoothly and giving them the added benefit of soaring at slower speeds. 

As well as his wings, this fellow is also drying off his white head feathers. A bald eagle's white head can make it look bald from a distance but that is not where the name comes from. It is from the old English word balde, meaning white.

In the Kwak'wala language of the Kwakiutl First Nations of the Pacific Northwest — or Kwakwaka'wakw, speakers of Kwak'wala — an eagle is known as kwikw (kw-ee-kw) and an eagle's nest is called a kwigwat̕si. 

Should you encounter an eagle and wish to greet them in Kwak'wala, you would just say yo. Yup, just yo. They would like your yo hello better if you offered them some fresh fish. They dine on all sorts of small mammals, fish and birds but are especially fond of pink salmon or ha̱nu'n (han-oon).

These living dinosaurs are a true homage to their lineage. They soar our skies with effortless grace. Agile, violent and beautiful, these highly specialized predators can catch falling prey mid-flight and dive-bomb into rivers to snag delicious salmon. 

Their beauty and agility are millions of years in the making. From their skeletal structure to their blood cells, today’s birds share a surprising evolutionary foundation with reptiles. 

Between 144 million and 66 million years ago, during the Mesozoic era, we see the first birds evolve. Eventually, tens of millions of years ago, an ancient group of birds called kites developed. Like today’s bald eagle, early kites are thought to have scavenged and hunted fish.

About 36 million years ago, the first eagles descended from kites, their smaller cousins. First to appear were the early sea eagles, which — like kites — continued to prey on fish and whose feet were free of feathers, along with booted eagles, which had feathers below the knee. Fossils of Bald Eagles are very rare and date to the late Pleistocene. Eagles are known from the early Pleistocene of Florida, but they are extinct species not closely related to the bald eagle.

Like the kites, bald eagles have featherless feet, but they also developed a range of other impressive adaptations that help them hunt fish and fowl in a watery environment. Each foot has four powerful toes with sharp talons. Tiny projections on the bottom of their feet called “spicules” help bald eagles grasp their prey. A bald eagle also has serrations on the roof of its mouth that help it hold slippery fish, and incredibly, the black pigment in its wing feathers strengthens them against breakage when they dive head first into water.

Obviously, there is much more than their striking white heads that sets these iconic raptors apart from the crowd. Their incredible physiology, built for life near the water, is literally millions of years in the making. 

TROPICAL BRITISH COLUMBIA: THE EOCENE

A reconstruction of BC's Early Eocene by Julius Csotonyi

British Columbia is blessed to have many fossil deposits that date back to the Eocene. This is the time in our Earth's history when our world was much warmer — about 13 degrees above what we are experiencing today. The dinosaurs had gone extinct by this point and we begin to see the dawn of modern animals filling that void. 

In the earliest portion of the Eocene, wee proto-hedgehogs smaller than your thumb lived in the undergrowth of British Columbia's forests. They shared the forest floor with an extinct tapir-like herbivore in the genus Heptodon that looked remarkably similar to his modern, extant cousins but lacked their pronounced snout (proboscis). I'm guessing that omission made him the more fetching of his lineage.

In both cases, it was a fossilized jaw bone that was recovered from the mud, silt and volcanic ash outcrops in the ancient lakebed at Driftwood Canyon. And these two cuties are significant— they are the very first fossil mammals we've ever found from the early Eocene south of the Arctic.

How can we be sure of the timing? The fossil outcrops here are found within an ancient lakebed. Volcanic eruptions 51 million years ago put loads of fine dust into the air that settled then sank to the bottom of the lake, preserving the specimens that found their way here. As well as turning the lake into a fossil making machine (water, ash, loads of steady sediment to cover specimens and stave off predation...) the volcanic ash contains the very chemically inert (resistant to mechanical weathering) mineral zircon which we can date with uranium/lead (U/Pb). The U/Pb isotopic dating technique is wonderfully accurate and mighty helpful in dating geologic events from volcanic eruptions, continental movements to mass extinctions.

The name Eocene comes from the Ancient Greek ἠώς and καινός and means "dawn." Subtropical forests covered much of the southern coast of British Columbia. Instead of the Spruce, Cedar, Hemlock and Fir that thrive across BC today, we had palms and large ferns. We find their remains as fossils, providing important clues to our ancient climate. 

From the northwest of British Columbia in an arc to our southeast is a grouping of Eocene deposits we refer to as the Okanagan Highlands. These are Eocene lakebed sites that extend from Smithers in the north, down to the fossil site of Republic Washington just south of the US border. The grouping includes the fossil sites of Driftwood Canyon, Quilchena, Allenby, Tranquille, McAbee, Princeton and Republic.

These sites range in time from Early to Middle Eocene, and the fossil they contain give us a snapshot of what was happening in this part of the world because of the varied plant fossils they contain.

We can infer the difference in climates between the sites. McAbee was not as warm as some of the other Middle Eocene sites, a fact inferred by what we see and what is conspicuously missing. 

In looking at the plant species, it has been suggested that the area of McAbee had a more temperate climate, slightly cooler and wetter than other Eocene sites to the south at Princeton, British Columbia and Republic and Chuckanut, Washington. Missing are the tropical Sabal (palm), seen at Princeton and the impressive Ensete (banana) and Zamiaceae (cycad) found at Republic in north-central Washington, in the Swauk Formation near Skykomish and the Chuckanut Formation of northern Washington state.

In all, the Eocene lasted from 56 to 33.9 million years ago. There was no ice on the planet. There was no Antarctic ice sheet. There was no Greenland ice sheet. There were no mountain glaciers; no ice whatsoever. It was just too warm to have what we call a cryosphere, which are the frozen parts of our planet where water is in solid form— sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets, and frozen ground. 

Without that ice to 'lock up' our abundance of water, sea levels were 70 meters higher during the Eocene— a significant difference that can be seen in the boundaries of our coastlines and what was and is waterfront property today.

Illustration: In a reconstruction of the early Eocene (52 million years ago) in northern British Columbia, a tapir-like creature from the genus heptodon drinks in the shallows, while a small proto-hedgehog stalks prey in the foreground. Created by the the hugely talented scientific illustrator, Julius T. Csotonyi and shared with permission.

BARNACLES: K'WIT'A' A

One of the most interesting and enigmatic little critters we find at the seashore are barnacles. They cling to rocks deep in the sea and at the waters' edge, closed to our curiosity, their domed mounds like little closed beaks shut to the water and the world.

They choose their permanent homes as larvae, sticking to hard substrates that will become their permanent homes for the rest of their lives. It has taken us a long time to find how they actually stick or what kind of "glue" they were using.

Remarkably, the barnacle glue sticks to rocks in a similar way to how red cells bind together. Red blood cells bind and clot with a little help from some enzymes. 

These work to create long protein fibres that first blind, clot then form a scab. The mechanism barnacles use, right down to the enzyme, is very similar. That's especially interesting as about a billion years separate our evolutionary path from theirs.

So, with the help of their clever enzymes, they can affix to most anything – ship hulls, rocks, and even the skin of whales. If you find them in tidepools, you begin to see their true nature as they open up, their delicate feathery finger-like projections flowing back and forth in the surf.

One of my earliest memories is of playing with them in the tidepools on the north end of Vancouver Island. It was here that I learned their many names. In the Kwak'wala language of the Kwakiutl First Nations of the Pacific Northwest, the word for barnacles is k̕wit̕a̱'a — and if it is a very small barnacle it is called t̕sot̕soma — and the Kwak'wala word for glue is ḵ̕wa̱dayu.

AMMONITE TRACE FOSSIL

This is a particularly fetching trace fossil of an ammonite in a septarian nodule.

Trace fossils or ichnofossils are burrows, footprints, tracks or even faeces left behind by plants and animals that lived long ago. 

Animals may have scurried across a muddy exposure or sea bottom, perhaps eaten a tasty meal then pooped it out — leaving behind clues to how they lived, what they ate and what the environment was like at the time. 

These are wonderfully informative clues to our ancient world.

ICE AGE MANATEES

Manatees do not live year-round in Texas, but these gentle sea cows are known to occasionally visit, swimming in for a summer vacation and returning to warmer waters for the winter. 

Interestingly, we have recently found fossil evidence for manatees along the Texas coast dating back to the most recent ice age. 

The discovery raises questions about whether manatees have been visiting for thousands of years, or if an ancient population of ice age manatees once called Texas home.

The findings were published in Palaeontologia Electronica by lead author Christopher Bell, a professor at the UT Jackson School of Geosciences with co-authors Sam Houston State University Natural History Collections curator William Godwin and SHSU alumna Kelsey Jenkins — now a graduate student at Yale University — and SHSU Professor Patrick Lewis.

The eight fossils described in the paper include manatee jawbones and rib fragments from the Pleistocene, the geological epoch of the last ice age. Most of the bones were collected from McFaddin Beach near Port Arthur and Caplen Beach near Galveston during the past 50 years by amateur fossil collectors who donated their finds to the SHSU collections.

The Jackson Museum of Earth History at UT holds two of the specimens. A lower jawbone fossil, which was donated to the SHSU collections by amateur collector Joe Liggio, jumpstarted the research.

Manatee jawbones have a distinct S-shaped curve that immediately caught Godwin's eye. But Godwin said he was met with scepticism when he sought other manatee fossils for comparison. He recalls reaching out to a local fossil enthusiast who told him point-blank, "there are no Pleistocene manatees in Texas."

But an examination of the fossils by Bell and Lewis proved otherwise. The bones belonged to the same species of manatee that visits the Texas coast today, Trichechus manatus. An upper jawbone donated by U.S. Rep. Brian Babin was found to belong to an extinct form of the manatee, Trichechus manatus bakerorum.

The age of the manatee fossils is based on their association with better-known ice age fossils and paleo-Indian artefacts that have been found on the same beaches.

It is assumed that the cooler ice age climate would have made Texas waters even less hospitable to manatees than they are today. But the fact that manatees were in Texas — whether as visitors or residents — raises questions about the ancient environment and ancient manatees. The Texas coast stretched much farther into the Gulf of Mexico and hosted wider river outlets during the ice age than it does today. Either the coastal climate was warmer than is generally thought, or ice age manatees were more resilient to cooler temperatures than manatees of today.

Subsurface imaging of the now flooded modern continental shelf reveals both a greater number of coastal embayments and the presence of significantly wider channels during ice age times.

If there was a population of ice age manatees in Texas, it is entirely plausible that they would have ridden out winters in these warmer river outlets similar to how they do today in Florida and Mexico.

Reference: Christopher Bell, William Godwin, Kelsey Jenkins, Patrick Lewis. First fossil manatees in Texas: Trichechus manatus bakerorum in the Pleistocene fauna from beach deposits along the Texas Coast of the Gulf of Mexico. Palaeontologia Electronica, 2020; DOI: 10.26879/1006

DUGONG: SEA COW

One of the most delightful creatures to ever grace this planet is the dugong — a species of sea cow found throughout the warm latitudes of the Indian and western Pacific Oceans. 

It is one of four living species of the order Sirenia, which also includes three species of manatees — their large, fully aquatic, mostly herbivorous marine mammal cousins.

The closest living relatives of sirenians are elephants. Manatees evolved from the same land animals as elephants over 50 million years ago. 

If not for natural selection, we might have a much more diverse showing of the Sirenia as their fossil lineage shows a much more diverse group of sirenians back in the Eocene than we have today. It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller's sea cow, was hunted to extinction in the 18th century. 

While only one species of the dugong is alive today – a second, the Steller's sea cow only left this Earth a few years ago. Sadly, it was hunted to extinction within 27 years of its discovery – about 30 species have been recovered in the fossil record

The first appearance of sirenians in the fossil record was during the early Eocene, and by the late Eocene, sirenians had significantly diversified. Inhabitants of rivers, estuaries, and nearshore marine waters, they were able to spread rapidly.

The most primitive sirenian known to date, Prorastomus, was found in Jamaica, not the Old World; however, more recently the contemporary Sobrarbesiren has been recovered from Spain. The first known quadrupedal sirenian was Pezosiren from the early Eocene. 

The earliest known sea cows, of the families Prorastomidae and Protosirenidae, are both confined to the Eocene and were about the size of a pig, four-legged amphibious creatures. 

By the time the Eocene drew to a close, the Dugongidae had arrived; sirenians had acquired their familiar fully aquatic streamlined body with flipper-like front legs with no hind limbs, powerful tail with horizontal caudal fin, with up and down movements which move them through the water, like cetaceans.

The last of the sirenian families to appear, Trichechidae, apparently arose from early dugongids in the late Eocene or early Oligocene. The current fossil record documents all major stages in hindlimb and pelvic reduction to the extreme reduction in the modern manatee pelvis, providing an example of dramatic morphological change among fossil vertebrates.

Since sirenians first evolved, they have been herbivores, depending on seagrasses and aquatic angiosperms, tasty flowering plants of the sea, for food. To the present, almost all have remained tropical — with the notable exception of Steller's Sea Cow — marine, and angiosperm consumers. Sea cows are shallow divers with large lungs. They have heavy skeletons to help them stay submerged; the bones are pachyostotic (swollen) and osteosclerotic (dense), especially the ribs which are often found as fossils.

Eocene sirenians, like Mesozoic mammals but in contrast to other Cenozoic ones, have five instead of four premolars, giving them a 3.1.5.3 dental formula. Whether this condition is truly primitive retention in sirenians is still under debate.

Although cheek teeth are relied on for identifying species in other mammals, they do not vary to a significant degree among sirenians in their morphology but are almost always low-crowned —brachyodont — with two rows of large, rounded cusps — bunobilophodont. The most easily identifiable parts of sirenian skeletons are the skull and mandible, especially the frontal and other skull bones. With the exception of a pair of tusk-like first upper incisors present in most species, front teeth — incisors and canines — are lacking in all, except the earliest sirenians.

THE CALL OF THE WILD: ANTARCTIC FUR SEALS

This little cutie is an Antarctic fur seal pup. He and his Mamma belong to the species Arctocephalus gazella — pinnipeds that live in dense colonies alongside King Penguins. 

These two call the South Georgia islands home, as do 95% of the world's fur seal population.  

Though a wee pup, he can already recognize her voice from all the other lovely Mammas in his busy, noisy colony. Little ones left on the rocky shores while their mother is out hunting will raise their heads and listen for their mother's voice. They can distinguish its vocal pitch over the loud calls of all the other busy Mammas and penguins of the colony. If you look closely, you can see his wee little ears. Antarctic fur seals, unlike some other seal species, have visible ears.  

Seal pups stay with their mother, relying on her lactation milk to help them fatten up and grow healthy and strong. For the first four months of their lives, their mother will feed them on her rich milk, then head out to sea to forage for food. 

Once she is back, she will call out to him and then give him a good sniff upon their reunion, the final confirmation for both parties that the right match has been made. The interaction between mother and pup is tender and heartbreakingly sweet to watch. She only gives birth to one pup (two is rare) each October to December. Pups are born with a sheen of fur and grow their waterproof fur during their first months of life. 

When this little fellow grows up, he will dine on fish, birds (including his penguin pals), squid and krill. Krill are small crustaceans of the order Euphausiacea that look like tiny shrimp. They look similar and are both crustaceans but shrimp hail from the suborder Natantia, order Decapoda and their hearts are located in their heads.

Krill live in all the world's oceans and sadly for them, they make a handy and tasty snack. They form an important part of the oceanic food chain. The krill feed on phytoplankton and zooplankton and then larger animals feed on the krill. 

Krill is Norwegian for small fry of fish. And they are small, indeed — but also tasty, nutritious and easy to catch. Once this little pinniped pup is out hunting on his own, krill will make up the majority of his adult diet. He will need our help to make sure he gets a steady supply. Krill are one of the casualties of ocean acidification from climate change. Hopefully, we will do better so they can, too.