Animal of the Week March 31, 2014 — How deep is your dive?

This week's animal of the week is a record-holding mammal, able to dive deeper or longer than any other. As reported in PLOS One, Ziphius curvirostris (Cuvier's beaked whale) can dive almost 3 km in depth remaining submerged for over 2 hours.

When George Cuvier first described this species, he thought it was an extinct species, but now they are known to be found around the world in all oceans except the high polar regions. The beaked whales are a widespread group of cetaceans, and despite there being quite a few species that are probably not uncommon, their open-ocean deep-diving habits mean they are poorly known—all but a few species having escaped the attention of the whaling industry, whence a lot of our knowledge of whales comes (not that that makes whaling a good thing). The northern bottlenose whale, one of which popped up the Thames to die back in early 2006, is also a species of beaked whale.

Beaked whales are named for their mouth, which notably protrudes from their head. They typically have only one pair of teeth and in many species these only erupt through the gums in the males—in older Cuvier's males these tusks protrude from the jaw, and combat between males are likely the cause of the parallel striations seen on the skin of many male whales. They hunt by sucking up squid and small fish on their forays into the deep ocean. To aid their impressive diving feats they have a very high proportion of myoglobin (the equivalent of haemoglobin that permeates muscle tissue), which keeps their muscle well oxygenated on deep dives, they are able to collapse the air cavities in their bodies on diving, and they have a very waxy blubber.

The previous record holder for mammal deep diving was an elephant seal that dove not quite as far for not quite as long—such is the nature of records. It's possible that other beaked whales and sperm whales dive even deeper, but until we know better, we salute you Cuvier's beaked whale. Great diving!

Animal of the Week March 16, 2014 -- first butterfly of the year

I'm a simple and predictable man. Just as I will let out a yelp of glee at the first bee of the season, the first sighting of a butterfly each year, usually a few weeks later, also elicits a broad grin. And that first butterfly is invariably this week's animal Gonepteryx rhamni (brimstone)—spotted this weekend in NW5.

The brimstone is somewhat unusual among UK butterfly species in that it hibernates as an adult, rather than migrating here from warmer climes, or overwintering as a pupa as many other butterflies do. This habit means it is often the first butterfly one sees in the year.

The brimstone is almost unmistakable. Other yellow butterflies, such as the rarer clouded yellows have substantial black markings on their wings and don't have the same, odd, geometrical wingshape of the brimstone.

The name brimstone obviously comes from their colour (related to sulphur, also known as brimstone, and yellow in colour). But oddly enough, one theory for the origin of the word butterfly is that it originated with the brimstone—ie, the butter-coloured fly.

However, a lot of other old words for butterfly in Germanic languages derive from a mediaeval belief that butterflies were witches in disguise that would steal unguarded milk, cream or butter; and this may be the true origin of the word. These words have been replaced with other terms related to Latin Papilio, but the German word for butterfly schmetterling is thought to derive from smetana, the Czech word for cream, and the belief that butterflies were milk-thieving witches.

Animal of the Week February 20, 2014 -- Holy carp!

When might a fish give you a black eye? When it's this week's animal of the week Hypophthalmichthys molitrix (silver carp), that's when.

This species made headlines this week when the US Government charged US Army Corps of Engineers to suggest ways in which they might prevent this invasive species from Asia reaching the Great Lakes, amid fears for the impact they and their close relative the bighead carp will have on these landmark ecosystems of the USA–Canada border.

Since their introduction to the southern Mississippi area of the USA three decades ago, they have made it all the way up the Mississippi, Missouri, and Illinois river systems. At points reaching phenomenal densities. Silver carp have a habit of leaping out of the water when spooked by loud noises such as boat engines, people have suffered broken noses, broken jaws, and broken vertebrae when hit by spooked fish. This video clip has no such outcomes but much good humour:

In Bath Illinois, the Redneck Fishing Tournament will  celebrate its 10th anniversary this year, in which people with nets catch the fish as they leap out of the water. The only rules: no fishing poles and do it at your own risk.

Silver carp are excellent filter-feeders, with specially designed gills that enable them to extract all but the tiniest particles from water. They can filter out particles 4 micrometres in diameter, have no need for stomachs because the particles they eat are so small, and they might never actually stop feeding. For this reason, they were introduced to the USA to help control algae in water treatment plants and catfish farms.

They can grow to a metre in length and reach 40 kg, and this ability to turn such tiny yet abundant food into so much body mass makes them ideal for farming, and they are the most farmed fish in the world. If you find that unbelievable because you've never seen a silver carp farm, but have fond childhood memories of trips to trout farms? That's because you've not grown up in China where most of the silver-carp farming happens.

Their habit of leaping out of the water

Previous introduced species AOTWs include the  snakehead and the harlequin ladybird.

Animal of the Week February 15 -- What the pangolin?!

How the hell have I been on AOTW for almost 10 years without once having a species of pangolin as feature?

It's World Pangolin Day, so I am going to make amends, and animal of the week is (picked somewhat at random from the eight extant species of pangolin) Manis gigantea (giant pangolin).

Known as scaly anteaters, pangolins do superficially resemble the bastard child of an anteater and pine cone, but
they are closely related to neither. In the tree of mammalian life, pangolins are somewhat out on a limb. They are most closely related to carnivores (cats, dogs, seals, weasels, etc), but have been on their own evolutionary path since the demise of the dinosaurs or thereabouts.

Pangolins, like anteaters, lack teeth, have cylindrical legs with strong claws, and have very long sticky tongues designed to extract ants and termites from their mounds. But this similarity is convergent evolution—it's one of the best ways to get at an abundant food source, so evolution has shaped several animals that way. When threatened by predators, pangolins curl up into a ball, protecting their heads and soft undersides with their hard scales.

The largest of all the pangolins, giant pangolins can weigh in excess of 30 kg and reach almost a metre and a half in length. Giant pangolins live from west Africa, through the Congo, to Uganda.

Some people hunt giant pangolins for bushmeat, and with habitat destruction, their numbers are in decline. Although the African pangolins fare slightly better than their Asian cousins. Their scales are highly prized in Chinese medicine and in parts of southeast Asia their flesh is considered a delicacy. The Asian pangolins are in a rapid decline, are some of the most trafficked animals, and may be destined for extinction before long. And as with the rhinos, also hunted to the brink for Asian medicine and ornament markets, once the Asian species go, traders will turn to Africa.

Animal of the Week Feb 4, 2014 -- extinction taketh away, but evolution (and scientists) giveth

It was with some joy that I recently read of a newly discovered species of river dolphin, Inia araguaiaensis (Araguaian river dolphin or Araguaian boto).

A close relative of former AOTW the Amazon boto, scientists taking a close look at the dolphins living in the Aruguaia–Tocantins river system noticed that they were a bit smaller than their relatives in the Amazon and had different jaw morphology. Some genetic studies revealed that the two populations had been separated for more than 2 million years and were likely different enough to be recognised as different species.

Animal of the Week isn't always (some would say "ever") a barrel of laughs. While I've made a lot of posts about new species described and discovered, I've had occasion to note a couple of extinctions along the way. The baiji is perhaps the most memorable no-longer species to feature as AOTW—this freshwater dolphin, erstwhile inhabitant of China's Yangtse river is thought to have gone extinct around 2006—the only species of whale or dolphin to be declared extinct in modern times, probably not the last.

River dolphins are not all c
losely related and are not confined to freshwater habitats. The true river dolphins (the botos, the plata dolphin, the baiji, and the south Asian river dolphin) are thought to represent a primitive group of species that once was also widely spread in marine habitats before the more modern dolphins arose and usurped them. The tucuxi lives in the Amazon and Orinoco rivers, but is more closely related to marine dolphins than to the river dolphins.

While there's some debate about whether the Araguaian boto is sufficiently different from the Amazon boto to be a completely separate species, but hey, give them another 2 million years and they will be.

Animal of the Week, January 13, 2014 -- swallow

This week's animal of the week is not a swallow, been there, done that.

But rather, a fish that swallows swallows. Researchers reporting in the Journal of Fish Biology have for the first time recorded video footage of this week's animal Hydrocynus vittatus (African tiger fish) leaping out of the water and catching one of the acrobatic birds as they skim the surface of a South African lake.

Not really a great deal to add to the video . The first video of the footage I saw lacked the banjo music, but I love banjos, and the highlighted video helps show where to look. Fish such as pike are known to take slow moving or stationary birds—all those coot chicks and ducklings that are there one day and gone the next. But this is the first fish known to catch birds in flight.

Well done that fish.

Animal of the Week September 20, 2013 — thrush with a taste for flesh

I often am amazed by just how many bleeding animals there are in the world, and despite my lifelong dedication to finding out about them, I can be totally astounded by something. I came across this week's animal of the week, appropriately enough, through Twitter: last week @BirdLife_News posed the question what's the smallest flightless bird (one extant/one extinct)?

Inaccessible Island rail: Brian Gratwicke

Now, the extinct one I knew, it's the Stephen's island wren, a tiny dot of a bird endemic to an island between the two large islands of New Zealand the last of which was killed by the lighthouse keeper's cat. That's one of the classic stories of extinction, one I'd heard and told many times before. But the living one was completely new to me: the Inaccessible Island rail. Not only did I not know there was an island called Inaccessible Island (part of the Tristan archipelago in the southern Atlantic, but also, I didn't know that living on it was the 17 cm, 30 g flightless relative of coots, moorhens, and the like*. Now rails are one of the most widespread groups of birds with species, some flightless, settled  on islands around the globe.

Tristan thrush: Brian Gratwicke

But it's not even the Inaccessible Island rail that's this week's animal. A quick google led me on a bit of a wikipedia trail. The rail has been able to miniaturise and lose the power of flight owing to the dearth of predators on inaccessible island. But nature abhors a vacuum, and eventually something will fill a vacant niche. And here we meet this week's actual animal, Nesicichla eremita (Tristan thrush; really it should be Turdus eremita, I am  picky). While it's mainland relatives are usually happy eating berries and insects with the occasional snail or worm thrown in, the Tristan thrush has developed a taste for seabirds, eggs, and chicks. Across the archipelago, the Tristan thrush raids the nests of petrels, rails, and even albatrosses (their eggs, not like a whole one); the thrushes have even evolved a brush like structure on their tongues to help them extract the filling of delicious seabird eggs.

Like the vampire ground finch of Wolf Island in the Galapagos, the Tristan thrush is another great example of how life on an island can lead to unexpected behaviour among unassuming looking creatures. Of course, if there was just a pharmacy on Inaccessible Island, the rails could get themselves a tube of canesten to rid themselves of their problem thrush.

*I used to really like coots, moorhens, crakes and gallinules, but not so much anymore. I've gone off the rails.