Showing posts with label grey. Show all posts
Showing posts with label grey. Show all posts

Sunday, January 14, 2024

GRAY WHALES: ESCHRICHTIUS ROBUSTUS

Young Gray Whale, Eschrichtius robustus
The lovely fellow you see here is a young Gray Whale, Eschrichtius robustus, with a wee dusting of barnacles and his mouth ajar just enough to show his baleen.

Two Pacific Ocean populations are known to exist: one of about 200 individuals whose migratory route is presumed to be between the Sea of Okhotsk off Russia's south coast and southern Korea, and a larger one with a population of about 27,000 individuals in the eastern Pacific.

This second group are the ones we see off the shores of British Columbia as they travel the waters from northernmost Alaska down to Baja California. Gray whale mothers make this journey accompanied by their calves, hugging the shore in shallow kelp beds and providing rare but welcome glimpses of this beauty.

The gray whale is traditionally placed as the only living species in its genus and family, Eschrichtius and Eschrichtiidae, but an extinct species was discovered and placed in the genus in 2017 — the Akishima whale, E. akishimaensis. Some recent DNA analyses suggest that certain rorquals of the family Balaenopteridae, such as the humpback whale, Megaptera novaeangliae, and fin whale, Balaenoptera physalus, are more closely related to the gray whale than they are to some other rorquals, such as minke. Still, others place gray whales as outside the rorqual clade, a kissing cousin if you will.

John Edward Gray placed it in its own genus in 1865, naming it in honour of physician and zoologist Daniel Frederik Eschricht. The common name of the whale comes from its colouration. The subfossil remains of now-extinct gray whales from the Atlantic coasts of England and Sweden were used by Gray to make the first scientific description of a species then surviving only in Pacific waters. The living Pacific species was described by American palaeontologist, Edward Drinker Cope as Rhachianectes glaucus in 1869.

Fin Whale, Balaenoptera physalus
Skeletal comparisons showed the Pacific species to be identical to the Atlantic remains in the 1930s, and Gray's naming has been generally accepted since. Although identity between the Atlantic and Pacific populations cannot be proven by anatomical data, its skeleton is distinctive and easy to distinguish from that of all other living whales.

In 1993, a twenty-seven million-year-old specimen was discovered in deposits in Washington state that represents a new species of early baleen whale. It is especially interesting as it is from a stage in the group’s evolutionary history when baleen whales transitioned from having teeth to filtering food with baleen bristles.

Visiting researcher Carlos Mauricio Peredo studied the fossil whale remains, publishing his research to solidify Sitsqwayk cornishorum (pronounced sits-quake) in the annals of history. The earliest baleen whales clearly had teeth, and clearly still used them. Modern baleen whales have no teeth and have instead evolved baleen plates for filter feeding. Look to the rather good close-up of this young Gray Whale here to see his baleen where once there was a toothy grin.

The baleen is the comb-like strainer that sits on the upper jaw of baleen whales and is used to filter food. We have to ponder when this evolutionary change —moving from teeth to baleen — occurred and what factors might have caused it. Traditionally, we have sought answers about the evolution of baleen whales by turning to two extinct groups: the aetiocetids and the eomysticetids.

The aetiocetids are small baleen whales that still have teeth, but they are very small, and it remains uncertain whether or not they used their teeth. In contrast, the eomysticetids are about the size of an adult Minke Whale and seem to have been much more akin to modern baleen whales; though it’s not certain if they had baleen. Baleen typically does not preserve in the fossil record being soft tissue; generally, only hard tissue, bones and teeth are fossilized.

Wednesday, March 9, 2022

SQUIRRELS: SHADOW TAILS

One of the little animals I see daily in Kitsilano, Vancouver, are the very busy, highly comic rodents we know as squirrels. 

They spend their days busily gathering and caching food and their nights resting from all that hard work. 

My neighbourhood has mostly Eastern Gray squirrels, Sciurus carolinensis (Gmelin, 1788) who come in a colour palette of reddish-brown, grey (British spelling) and black. 

These cuties have bushy tails and a spring in their step — racing around gathering nuts, finding secret hiding spots to cache them, teasing dogs and generally exuding cuteness.

We find the first fossil evidence of tree squirrels in the Pleistocene. At least twenty specimens have been found of Sciurus carolinensis in Pleistocene outcrops in Florida on the eastern coast of the United States. Over time, their body size grew larger then shrunk down to the 400 to 600 g (14 to 21 oz) weight we see them today.  

Eastern Gray squirrels have two breeding seasons in December-January and June-July. This year has been unseasonably warm. On Vancouver Island, the Eastern Grays bred again in early September. One wonders if the heat dome killed off the July litter, and with the return of more favourable weather, the parents have been induced to breed again.

While they are not native to Vancouver, they are plentiful. They were introduced to the region over a hundred years ago and have been happily multiplying year upon year. 

Our native species are the smaller, reddish-brown, rather shy Douglas squirrels, Tamiasciurus douglasii (Bachman, 1839), and the nocturnal Northern Flying Squirrels, Glaucomys sabrinus (Shaw, 1801).  

Sciurus, is derived from two Greek words, skia, meaning shadow, and oura, meaning tail. The name choice is poetic, alluding to squirrels sitting in the shadow of their tails. 

The specific epithet, carolinensis, refers to the Carolinas on the eastern seaboard of the United States, an area that includes both North and South Carolina. It was here that the species was first recorded and still rather common. In the United Kingdom and Canada, Sciurus carolinensis is referred to as the Eastern Gray or grey squirrel — and though adorable is an invasive species. 

In the United States, Eastern is used to differentiate the species from the Western Gray or Silver-Gray squirrel, Sciurus griseus, (Ord, 1818). 

The Ord here, of course, is George Ord, the American zoologist who named the species based on notes recorded by Lewis and Clark in the early 1800s. If you fancy a read, check out his article from 1815, "Zoology of North America." It is charming, anachronistic and the first systemic zoology of America by an American. 

In the Kwak̓wala language of the Kwakiutl or Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest, use the word ta̱minasux̱, to express: "that is a squirrel." 

The word for shadow in Kwak'wala is gagumas and tail is ha̱t̕sa̱x̱ste' — so I will think of these wee wonders of the Order Rodentia in the family Sciuridae as the Gagumas ha̱t̕sa̱x̱ste' of Khahtsahlano. 

Monday, November 15, 2021

BLADDER-BEARERS: HOODED SEALS

If you frequent the eastern coast of North America north of Maine to the western tip of Europe, along the coast of Norway near Svalbard you may have glimpsed one of their chubby, dark silver-grey and white residents. 

Hooded seals, Cystophora cristata, are large phocid seals in the family Phocidae, who live in some of the chilliest places on Earth, from 47° to 80° N in latitude. 

These skilled divers are mainly concentrated around Bear Island, Norway, Iceland, and northeast Greenland. 

In rare cases, we find them in the icy waters in Siberia. They usually dive depths of 600 m (1,968 ft) in search of fishy treats but can go as deep as 1000 m (3,280 ft) when needed. That is deep into the cold, dark depths of our oceans. Sunlight entering the sea may travel as deep as 1,000 m (3,280 ft) under the right conditions, but there is rarely any significant light beyond 200 meters (656 ft). This is the dark zone and the place we find our bioluminescent friends. 

Hooded seals have a sparse fossil record. One of the first fossils found was a Pliocene specimen from Anvers, Belgium discovered in 1876. In 1983 a paper was published claiming there were some fossils found in North America thought to be from Cystophora cristata. Of the three accounts, the most creditable discovery was from a sewer excavation in Maine, the northeasternmost U.S. state, known for its rocky coastline, maritime history and nature areas like the granite and spruce islands of Acadia National Park. A scapula and humeri were found among other bones and thought to date to the post-Pleistocene. 

Of two other accounts, one was later reassigned to another species and the other left unsolved. (Folkow, et al., 2008; Kovacs and Lavigne, 1986; Ray, 1983)

The seals are typically silver-grey or white in colour, with black spots that vary in size covering most of the body. 

Hooded seal pups are known as, Blue-backs as their coats are blue-grey on the back with whitish bellies, though this coat is shed after 14 months of age when the pups moult.

FIRST NATION, INUIT, METIS, MI'KMAQ L'NU

In the Kwak̓wala language of the Kwakiutl or Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest, seal are known as migwat — and fur seals are known as x̱a'wa.

Hooded seals live primarily on drifting pack ice and in deep water in the Arctic Ocean and North Atlantic. Although some drift away to warmer regions during the year their best survival rate is in colder climates. They can be found on four distinct areas with pack ice: near Jan Mayen Island, northeast of Iceland; off Labrador and northeastern Newfoundland; the Gulf of St. Lawrence; and the Davis Strait, off midwestern Greenland. 

The province of Newfoundland and Labrador is home to the Inuit, the Innu, the Mi'kmaq L'nu and the Southern Inuit of NunatuKavut, formerly the Labrador Inuit-Metis. The Hooded Seals that visit their traditional territory were a welcome source of food and clothing. In Mi'kmaw, the language spoken in Mi'kma'ki, the territory of the Mi'kmaq L'nu, the word for seal is waspu.

HOODED SEAL HABITAT

Males are localized around areas of complex seabeds, such as Baffin Bay, Davis Strait, and the Flemish Cap. Females concentrate their habitat efforts primarily on shelf areas, such as the Labrador Shelf. 

Females reach the age of sexual maturity between two and nine years old and it is estimated that most females give birth to their first young at around five years of age. Males reach sexual maturity a little later around four to six years old but often do not mate until much later. Females give birth to one young at a time through March and April. The gestation period is 240 to 250 days. 

Blue-back, Hooded Seal Pup
During this time the fetus, unlike those of other seals, sheds its lanugo — a covering of fine soft hair that is replaced by thicker pelage — in the uterus. 

These young are precocious and at birth are able to move about and swim with ease. They are independent and left to fend for themselves immediately after they have been weaned.

Hooded seals are known to be a highly migratory species that often wander long distances, as far west as Alaska and as far south as the Canary Islands and Guadeloupe. 

Prior to the mid-1990s, hooded seal sightings in Maine and the east Atlantic were rare but began increasing in the mid-1990s. From January 1997 to December 1999, a total of 84 recorded sightings of hooded seals occurred in the Gulf of Maine, one in France and one in Portugal. 

From 1996 to 2006, five strandings and sightings were noted near the Spanish coasts in the Mediterranean Sea. There is no scientific explanation for the increase in sightings and range of the hooded seal.

Cystophora means "bladder-bearer" in Greek and pays homage to this species' inflatable bladder septum on the heads of adult males. The bladder hangs between the eyes and down over the upper lip in a deflated state. 

The hooded seal can inflate a large balloon-like sac from one of its nostrils. This is done by shutting one nostril valve and inflating a membrane, which then protrudes from the other nostril. 

I was thinking of Hooded seals when contemplating the nasal bladders of Prosaurolophus maximum, large-headed duckbill dinosaurs, or hadrosaurid, in the ornithischian family Hadrosauridae. Perhaps both species used these bladders in a similar manner — to warn predators and attract mates.

Hooded seals are known for their uniquely elastic nasal cavity located at the top of their head, also known as the hood. Only males possess this display-worthy nasal sac, which they begin to develop around the age of four. The hood begins to inflate as the seal makes its initial breath prior to going underwater. It then begins to repetitively deflate and inflate as the seal is swimming. 

The purpose of this is acoustic signalling. It occurs when the seal feels threatened and attempt to ward off hostile species when competing for resources such as food and shelter. It also serves to communicate their health and superior status to both other males and females they are attempting to attract. 

In sexually mature males, a pinkish balloon-like nasal membrane comes out of the left nostril to further aid it in attracting a mate. This membrane, when shaken, is able to produce various sounds and calls depending on whether the seal is underwater or on land. Most of these acoustic signals are used in an acoustic situation (about 79%), while about 12% of the signals are used for sexual purposes.

References: Ray, C. 1983. Hooded Seal, Cystophora cristata: Supposed Fossil Records in North America. American Society of Mammalogists, Vol. 64 No. 3: 509-512; Cystophora cristata, Hooded Seal", 2007; "Seal Conservation Society", 2001; Kovacs and Lavigne, 1986.

Mi'kmaq Online Dictionary: https://www.mikmaqonline.org/servlet/dictionaryFrameSet.html?method=showCategory&arg0=animal