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.