Most of the animal victims of BP’s spill that we see on TV are cuter surface dwelling animals and those of the shallow water – pelicans, dolphins and turtles in particular. With some of the oil suspended in the water column and more settling onto the ocean floor, ecosystems other than the shallow water and shore are set to be hard hit.
If you’re a fisherman you’ve almost certainly seen an isopod or two. When I was a teenager I would regularly find them in the mouths of yellowtails, where they had sucked blood from the fish’s tongue for so long the tongue withered and died. The isopod would then live on, replacing the tongue while sharing in the fish’s food.
You probably haven’t met Bathynomus giganteus, their somewhat larger relative (picture at right). Practical Fishkeeping has an article billing them as the world’s most disgusting creatures. The article does not include care instructions, and I suspect they don’t appear in aquarium shops very often. Bathynomus grows to around 75cm in length, and are thought to feed on carcasses that have sunk to the bottom of the deep ocean.
Nature is carrying an interesting article about the recovery of Lake Victoria’s cichlids. I trace my passion for aquariums in general and cichlids in particular back to Tijs Goldschmidt’s book Darwin’s Dreampond: Drama in Lake Victoria, which discussed the evolution of the Lake Victoria cichlids and the catastrophic results of introducing the Nile Perch (which is in the same genus as barramundi) to the Lake.
Recent research suggests some species which survived the arrival of the predator have managed to return to parts of the Lake from which they had been driven.
What caused the cichlids’ return is uncertain, but it is probably a combination of fishing pressures on the Nile perch and some measures taken to reduce pollution in the lake, coupled with the cichlids’ own capacity for adaptation.
Nobody is complacent about the recovery, however. Oliva Mkumbo, a senior scientist at the Lake Victoria Fisheries Organization in Jinja, Uganda, says that the water quality may have stopped deteriorating, thanks in part to the construction of new sewage works, but deforestation and erosion are still major problems. As Seehausen puts it, eutrophication could still “close the show”, resulting in an even more catastrophic collapse of cichlid biomass and diversity.
Reading through the April issue of Practical Fishkeeping (it takes a while for the UK magazine to hit the shelves here) I noticed a brief article mentioning research by Lukasz Pasco of the University of Wroclaw in Poland. His paper, Tool-like behavior in the sixbar wrasse, Thalassoma hardwicke, published in Zoo Biology, describes the sixbar wrasse smacking large pellets of food against rocks in order to break them intoo smaller pieces to eat.
I was a bit surprised. This is news? My moon wrasse (Thalassoma lunare) does that all the time. I give her Hikari Cichlid Gold large pellets regularly and watch her smash them against the rocks in the tank. It didn’t occur to me until reading the article that this behaviour is unique among my fish. I’ve seen many of my smaller cichlids trying to deal with the large pellets, but I’ve never seen one use a rock.
Unfortunately it isn’t of brilliant quality, but here’s a video of the behaviour in question:
It’s certainly interesting behaviour, though I’m not sure if it should be classified as tool use. Both species are from the same genus, so I’m wondering if other people have seen the same behaviour in other Thalassoma, in other genera of wrasse, or in other families of fish.
The sixbar wrasse is a very common sight when snorkelling on the Reef, and willl often be found swimming along behind snorkellers trying to feed on organisms in sediment kicked up by a snorkeller’s fins. It’s the only wrasse I’ve found doing that, though sergeants do the same.
Tool-like behavior in the sixbar wrasse, Thalassoma hardwicke
A nightclub in England recently had a revamp and decided that their resident fish were no longer required. Toko’s giant gourami (illegal in Australia) and two catfish had called the nightclub home for ten years, but will now reside at the Brighton Sea Life Centre.
After being exposed to years of pounding drum’n'bass music, there was concern that the fish may not feel comfortable in their new surroundings straight away, so the staff are making sure that they continue to receive regular drum’n'bass sessions. They’ll slowly be weaned onto their new, quieter environment.
Fish experts believed that the gradual reduction of vibrations would help the fish to settle in and recently conducted research would suggest that fishes ‘happiness’ may be affected by the sounds they hear and are exposed to.
I decided that today would be very lazy. I had a bit of a sleep in, fetched some water for my marine tanks, then crashed on the beach with a bacon and egg sandwich, some orange juice, and Why does e=mc² by Brian Cox and Jeff
Not sure what species this is, but they seem to like human skin
Forshaw. After a while I wandered slowly to the northern end of the beach, allowed some fish (one pictured at right) to try eating the skin from my lower legs, watched a sea eagle eat its lunch, then wandered back to the cafe again for an iced chocolate and some mango and macadamia cheesecake.
I may wander back to the beach for a bit this afternoon, maybe with the Skeptics’ Guide to the Universe and a Malibu and cola. Yes, it’s a tough life.
Here’s another small fish I found in a rock pool at Taylor Point. Scouring my books hasn’t been helpful, and I suspect the adult form may be somewhat different from the juvenile form. I was initially thinking it was a rabbitfish, but I’m less confident of that now.
The 1cm long fish above is the one I was chasing when I took my Christmas Day tumble, and ended up in hospital getting X-rays of my arm. My wounded arm and hip are healing slowly, while the fish is gaining weight quickly. It seems to be enjoying captivity, and has quickly become quite tame and relaxed. This shouldn’t be too surprising as sergeants seem to be the most common fish (with six-barred wrasses second) to follow snorkellers around the reef looking for food kicked up by the snorkeller’s fins.
Here’s a video from the American Museum of Natural History about the evolution of fish species in the lower Congo River. It shows how fish in one body of water can nevertheless be genetically isolated by conditions within that body of water, which allows for speciation events and greater species diversity. The main fish in this study are from the Teleogramma genus, T. brichardi, T. gracile, and T. depressum.
You can email your complaints, abuse and insults to me by reversing moc.emohqnf@emohqnf to get my email address.
Random Quote
If you hold views about a supernatural realm that have absolutely no empirical consequences whatsoever then you have nothing to fear from science. There are even certain religious systems that posit such a realm. But that is not the sort of faith held by most Christians. — Jason Rosenhouse
