Monday, 22 August 2016

New series: Indian Dwarf Mudskipper

Indian Dwarf Mudskipper
After a long break, I have decided to restart this blog with an updated series on the aquarium at Bristol Zoo. There has been a major rebuild of the large tanks and other changes in the displays, but I will start with a new display of one of the oddest fish in the sea, the Indian Dwarf Mudskipper Periophthalmus novemradiatus.

 There are over 30 species of mudskippers around the world, almost all of them in south east Asia, but some species are found in east Africa and one species is found in west Africa. Mudskippers are actually a highly specialised group of gobies, familiar from rockpools around the world. Gobies tend to be very small fish, and spend a lot of time in concealed holes or burrows depending on the species. The typical habitat for mudskippers is mangrove swamps and mudflats, and where they are found they are often very numerous and are a major prey item for fish eating birds such as kingfishers. The largest species can be up to 30cm, but the species on show at Bristol is one of the smallest at under 7cm.

West African Mudskippers
The unique lifestyle of mudskippers is completely attuned to the changing tides, and the lack of protection on the exposed mudflats. They compensate for this by constructing burrows into the mud which they maintain at low tide and conceal themselves in when the tide rises. When the tide goes down they emerge to feed on small crustaceans, other small prey items, and in some species algae growing on the surface of the mud. When the tide comes in the burrows provide safety, but at the cost of a serious problem with respiration. The mud the burrows are in is highly anoxic and full of poisonous hydrogen sulphide, and oxygen levels in the burrows drop to the point of suffocation very quickly.

The mudskippers cope with this by use of their ability to absorb oxygen from atmospheric air. While the tide is out they take mouthfuls of fresh air deep into the flooded burrows to create an air pocket deep in the mud, and when the tide comes in they can continue to breathe air even when deep underwater.

Reproduction in mudskippers involves care of the eggs in the burrow, but of course eggs are if anything even more vulnerable to the toxic environment of the burrow water than the adults. Mudskippers solve the problem by laying their eggs out of water in a special egg chamber extension to the burrow. In the species studied so far, it is the male that constructs and guards the breeding burrow and keeps the egg chamber full of air when the eggs are developing. When the eggs are due to hatch, he floods the burrow to cause the eggs to hatch and the larvae make their way to the entrance, entering the plankton on the rising tide.

While mudskippers are quite widely kept in both public aquaria and by private aquarists, up to now there has been no successful breeding. This is the result of their highly specialised behaviour, but there are more aquarists attempting to replicate their environment in dedicated tanks, and I have found at least one record of larvae being produced, though not yet reared to metamorphosis.

For a video of the breeding burrow see this Youtube video of a breeding male:

Next time, I will begin a survey of the inhabitants of the new large marine tank in the Aquarium, now home to a very interesting range of species.

Images from wikipedia

Friday, 21 August 2015

Plight of the Bumblebee 2: Commerce and conservation

B.lapidarius in my garden
When people talk about the vital importance of bees for pollination and agriculture, the only species that is usually thought about is the honeybee. For many crops however, both those grown in field and those in glasshouses, bumblebees and other wild bees are vastly more important. While honey bees are pretty generalist feeders, visiting many types of flower, they are not good at pollinating many species and are incapable of pollinating some crops at all, of which the Solanaceae (tomatoes, chilli peppers, aubergines etc.) are the most obvious. These require “buzz pollination”, where the bees vibrate the anthers to release pollen.  Other important crops which benefit from this type of pollinator rather than honey bees include blueberries, cranberries, and also kiwifruit. Even apples seem to be better pollinated by bumblebees that honeybees, as honey bees approach the flower in such a fashion that pollen is not efficiently moved from flower to flower. In addition, honeybees will not fly in cool or wet weather, which reflects their essentially tropical to subtropical origins. Bumblebees by contrast are adapted to cool climates, and will fly in cold weather or even in rain.

Tuesday, 11 August 2015

Plight of the Bumblebee Part 1: Lifecycle

B.terrestris worker
Aside from the honeybee, just about the only wild bee species most people in Britain are able to name are the large, furry bumblebees in the genus Bombus. With 24 species in the UK, and around 250 worldwide, they are a small but conspicuous minority of the several hundred species wild bee species in the UK. Aside from bumblebees and honeybees, the other species are all solitary, with a single female provisioning their nest, usually in a hole which may be excavated in the ground, wood, or simply a hollow stem.

Saturday, 11 July 2015

New Arrival: White-Belted Black and White Ruffed Lemur

Now on show at Wildplace is a new addition to their lemur collection, a young paid of the Northern or White-Belted Black and White Ruffed Lemur, Varecia variagata subcincta. This is one of three subspecies of V.variagata, plus the only other species of Varecia, the Red Ruffed Lemur V.rubra. Bristol Zoo has two V.rubra that are hand tame and are used in their daily animal displays, but these are non-breeding animals. The Wildplace pair will hopefully breed in the future, as they are a young pair.

Thursday, 25 June 2015

On the Wing: The Large Blue Butterfly

Last Saturday I finally managed to see the Large Blue Phengaris (Maculinea) arion at Collard Hill Hill reserve in the Mendips. As they are on the wing for perhaps another week or so, there is not much of a time window to see one this year. As one of the rarest of British butterflies, and with one of the weirdest lifecycles of any butterfly, it is definitely one to look for.