Wednesday, February 20, 2019

Animal of the Week, February 20, 2019 — When is a sea slug like a leaf?

Karen N. Pelletreau et al
This week's animal of the week Elysia chlorotica is a peculiar sea slug. First off it's not a nudibranch like the other familiar sea slugs. Instead it is a member of a different branch of the gastropod class.

The main thing about this particular marine mollusc is that it can photosynthesise for long periods of time. Various animals, notably corals, form symbiotic relationships with algae in which the the animal provides a home and protection for algae and the algae provide food for the animal. But this curious sea slug goes a step further—it eats a particular type of algae, Vaucheria litorea, and actually assimilates chloroplasts, tiny light absorbing subcellular units that make energy from sunlight.

Other relatives of E chlorotica do the same, but usually, the choloroplasts, lacking the supportive environment of the algae die in a few days. Somehow, E chlorotica keeps the algae alive for months, sometimes until the sea slug itself reaches old age and dies. The thing I find most pleasing about this whole arrangement is how much like a leaf this sea slug looks.

E chlorotica lives in a vanishingly small range on the eastern seaboard of the USA, and it's poorly studied. How it keeps the chloroplasts functioning for so long might be because the slug itself has integrated some of the algal genes that support the chloroplasts, although the science on this is out. And the rareness of the animal and the difficulties with studying it in the lab mean answers might not be forthcoming any time soon.

Picture source:

Tuesday, February 05, 2019

Animal of the Week, February 5, 2019 — one of our pandas is missing

A little bit belatedly to this week's animal, for it is the red panda (Ailurus fulgens), one of which had a brief excursion in the Northern Irish city of Belfast. This particular fluffball escaped from Belfast Zoo on Sunday January 27 had a merry stroll around the area of Glengormley before being captured on Monday an returned to its enclosure.

Poor panda must have been pretty confused, because Belfast (although I have never been) can't be much like the temperate montane forests of the Himalayas (Nepal, Tibet, and India) and Burma and China whence the red panda originates. Although their ranges and food sources overlap, red pandas aren't that closely related to giant pandas. In a family of their own (Ailuridae), red pandas are more closely related to raccoons, skunks, and weasels than to bears, the family to which giant pandas belong.

Nonetheless, both species of pandas have endearing facial markings and a penchant for bamboo. Another quirk possessed by both species is the so-called panda's thumb. Not a thumb at all, but a projection of a wrist bone, the appendage helps both species grasp onto and manipulate bamboo while feeding.

Both species of panda are also endangered, with wild individuals threatened by habitat loss and poaching. But fortunately for both species, their attractiveness makes them popular zoo animals and captive breeding programmes can help to conserve red panda, which is somewhat more reliable as a breeding animal in captivity than it's black and white namesake.

The Latin name, Ailurus fulgens, means "shining cat".

The zoo escape gave a brief foray into the urban environment for the panda and a tiny bit of a break from Northern Ireland only ever being mentioned in conjunction with the word "backstop". Still, the pandas home now and normal service has resumed.

Wednesday, January 23, 2019

Animal of the Week, January 23, 2019—megacharm

Gonna be a brief one this week, because, well, the numbers speak for themselves. A flock of 5 million bramblings (Fringilla montifringilla) have gathered in a patch of trees with a radius of about 250 m (5 hectares) in Slovenia southern Europe.

These beautiful little finches breed in the taiga forests of northern Eurasia and in winter head south to feed on beech and hornbeam seeds in the forests of more temperate regions (a few birds make it to the UK each winter). Extreme weather in central Europe has covered potential food there in metres of snow forcing all the birds that would normally spread out across the region to head south. Droughts earlier in the year mean that potential winter food is limited to densely forested regions such as Slovenia. The full explanation and amazing pictures of the megacharm is available on Rare Bird Alert.

Bramblings are closely related to chaffinches, to which they bear a passing resemblance. A group of finches is known as a charm—so I'm calling this a megacharm. The origin of the name brambling is uncertain, perhaps related to brambles, or perhaps to brandling (the striped worms that you find in your compost bins). I have never seen a brambling, but would very much like to one day as they are, I hope you agree, quite stunning birds.

Tuesday, January 08, 2019

Animal of the Week, January 8, 2019 — probably the rarest bird in the world

This week's animal currently holds the title of the rarest bird in the world. The Madagascar pochard (Aythya innotata) is an unassuming brown duck, so unremarkable in appearance it went unremarked for years. Long thought to be a Madagascan wing of the ferruginous duck family, it was not recognised as a distinct species until 1894. 100 years later, by the mid-1990s the Madagascar pochard was thought to be extinct. Then, in 2006 a tiny remnant population was discovered on a remote lake in Madagascar.

Lake Matsaborimena, where the nine adults and a handful of chicks clung to life was far from ideal and the dwindling population would likely have vanished without intervention. Clutches of eggs were collected from the wild and hand-reared in captivity. In late December, 21 birds were released onto Lake Sofia, a more suitable habitat. Conservationists from the Wildfowl and Wetlands Trust, Durrell Wildlife Conservation Trust, The Peregrine Fund and the Government of Madagascar have worked with local communities to give the reintroduced birds the best chance.

With around about 90 individuals in the world, there's probably no rarer bird. Other thoroughly uncommon birds includ the Spix macaw, which has a similar number, all in captivity, and the kakapo, the flightless New Zealand parrot which is now up to about 130 birds on predator free island refuges surrounding New Zealand.

Tuesday, January 01, 2019

Animal of the Week January 1, 2019 — not a giraffe

What do the Thames and Melania Trump's twitter feed have in common?

They both have an unexplained beluga whale in them.

Beluga whales (Delphinapterus leucas) are a an Arctic species that live in groups around the ice cap in winter but then move to estuaries and coastal waters when ice recedes in summer. Although these seasonal migrations mean that beluga whales do get about a bit, they are unexpected visitors so far south as the UK, let alone the southeast of England. Nonetheless, here we are, with a lone beluga whale pratting around near Gravesend, first identified in September, the whale was probably actually first sighted in August.

What brought the beluga whale to the Thames is a mystery, as is the 2012 tweet from Melania Trump, in which the first lady, pondered "What is she thinking?" Odd enough in itself, but then on Sunday night just gone, the tweet miraculously changed so that the photo of the whale was replaced with one of a giraffe. "WTF?!", the twittersphere thought. "Can the Trumps now edit their old tweets?" But then to further muddy the waters, the giraffe was showing up on some browsers and not on others, turns out it was some coding glitch that I won't pretend to understand. Order has been restored and the whale is back as it should be. But what is she thinking? Melania, the whale, the giraffe?

Beluga whales are part of the toothed whale family and their closest relatives are narwals. The name, beluga, comes from the Russian for "white", which is also the origin for the name of the beluga sturgeon, whence the caviar. Sturgeon and whale are no more closely related than any other mammal and fish. Known as the canary of the sea for their high-pitched vocalisations, belugas are unfortunately frequently kept in captivity, which is no place for a cetacean, but one or two captive belugas have been able to mimic human speech patters—what clever fellows.

News that a beluga whale was spotted in the Thames brought back memories of Wally the Whale, a northern bottlenose whale that found itself stranded in Vauxhall, exhausted and disoriented (god knows I know that feeling). While the newest cetacean visitor seems to be thriving, Wally was less fortunate and died (god knows I know that feeling).

Wednesday, August 09, 2017

Animal of the Week, August 9, 2017—new grass snake, you're barred! Aug 9, 2017
You can't have failed to notice the news come alive this week with reports of a new species of grass snake identified in the UK. Amazing, stunning! The new species (the barred grass snake; Natrix helvetica) can be distinguished by its less pronounced collar, more pronounced barring along its body, and less vibrant colour (khaki rather than green) compared with other grass snakes (Natrix natrix). Several news outlets reported that the addition of the new species raised the number of snake species living in the UK from three (adder, grass snake, and smooth snake) to four (those three plus the barred grass snake).

But hold on! Should you be asked, in say, a pub quiz, how many species of snake are native to the UK, the answer is still three. If, indeed, the barred grass snake is a separate species, it is the only grass snake species in the UK. The barred grass snake's range in Europe can largely be described as north of the Alps and Pyrenees and west of the Rhine, no other grass snakes are found in this area.

From the original research paper, the blue symbols show the distribution of Natrix natrix helvetica

Scientist analysed genetic samples from snake skins, roadkill, and museum specimens across the northern and eastern European rang of the grass snake. According to the research, the barred grass snake should be recognised as a distinct species from the other subspecies in the Natrix natrix group: whereas the other subspecies have substantial range overlap in which they crossbreed, interbreeding between helvetica and its neighbour natrix is very rare.

Font fans and graphic designers will find it ironic that the helvetica species is distinguished by its pronounced bars.

Wednesday, August 02, 2017

Animal of the Week, August 2, 2017—could krill save the world?

In the Animal of the Week archives, charismatic birds and mammals far outweigh other creatures, and invertebrates especially are fairly lightly represented. This week let's go some way to reddress that imbalance. By weight, Antarctic krill (Euphausia superba), are the single most abundant animal on Earth.

The most recent AOTW, blue whales, might be the largest animal ever to have lived, but if you were collect all the blue whales together, they might just tip the (very large pair of) scales at approaching 1 million tonnes, all the Antarctic krill in the world would weigh almost 500 times as much—which is just as well, because they are the main source of food for blue whales and numerous other species.

The total numbers of krill in this half a billion tonnes are immense—as many as 500 trillion (that's half a quadrillion) might be alive at any one time. They form swarms of immeasurable number, although the density of these swarms can reach 30 000 individuals per cubic metre. As you might expect for something that exists in such a multitude the individuals are pretty small: the bioluminescent free-swimming shrimp like creatures might reach 6 cm in length and weigh up to 2 grammes.

The importance of Antarctic krill to the world probably cannot be overstated—as well as providing the main food source of a host of whales, seals, penguins, seabirds, fish, and squid, they are thought to be key players in the global carbon cycle and, as such, probably have an important role in moderating climate. Krill migrate up and down the water column, rising to the surface to feed on microscopic plants (phytoplankton) and some animals (zooplankton) but when they are full, they stop swimming and sink while they digest their food (same). The outcome of this is that they transfer carbon from the surface of the water (trapped in photosynthesising plants) to the lower levels (as faeces and their own bodies). The krill's waste sinks to the ocean floor where it is sequestered—were the krill not dragging the carbon down, the plankton would decay in the surface waters releasing greenhouse gases to the atmosphere.

As well as providing food for a multitude of sea creatures, krill are also popular with people—in Japan and Korea krill have been consumed as food for a while, but in the past couple of decades krill oil has become a popular dietary supplement and krill products are increasingly used in aquaculture as fish food and in other pet foods. But given their role in ocean food webs and the potential impact on climate change of depleting krill numbers, we must be careful not to overexploit the remarkable creatures.