Micro-rock-pooling in Winter.

It's too cold in winter to spend a lot of time paddling around in rock pools but you can always take a few samples of seaweed home on a jar of seawater and have a look at the smaller inhabitants under the microscope. These two, each about a millimetre long, were in a  sample of Corallina officinalis seaweed. The upper specimen is an unusually bristly acarine mite, found clambering through the seaweed fronds. You can see more acarine mites by clicking here.

This is a minute flatworm, with two very simple eyes, found gliding over the surface of the seaweed, propelled by thousands of cilia that are only visible at high magnification under the microscope. You can see another marine flatworm, in more detail and with a movie of the cilia in action, by clicking here.

Micro-rock-pooling

This is probably the low point of the year for exploring life in seaside rock pools but if you search amongst the fronds of seaweeds like the red Ceramium and green Cladophora, that can still be found on sheltered parts of the shore, and take them home for microscopic examination you can still find a wealth of marine life in miniature. Here, beautifully camouflaged in a flecked green exoskeleton, is a sea slater Idotea sp.

The multi-facetted compound eye of Idotea is exceptionally beautiful.

In amongst the weed and hanging from the surface film in the rockpool you'll almost certainly find large numbers of juvenile gastropod molluscs, each only a couple of millimetres long - this one is almost certainly a Littorina (winkle) species. Notice the single dark eye at the base of each antenna.

Acarine mites are incredibly diverse animals that live in almost every habitat imaginable (click here for more information on them). Scores of these little 8-legged animals, each only about a millimetre long, were scurrying around amongst the seaweed fronds. Not much is known about the ecology of marine mites, which mostly belong to a single family - the Halacaridae. Notice the long, hooked claws that stop them from being washed out of their seaweed shelter, and the piercing mouthparts at the head end. There's a short video clip below.

You can find more on freshwater marine mites here.

Mitey Fine Claws

This little animal is an acarine mite - a minute but close relative of the more familiar spiders. Both have eight legs but mites are arachnids with a simple globular body, unlike spiders whose bodies are divided into a thorax that bears the legs and an abdomen, separated by a narrow waist. Terrestrial mites are present in vast numbers in damp vegetation at soil level, while aquatic species are in just about every pond. The land living species like those pictured here are equipped with impressive claws (bottom photo), reminiscent of Captain Hook’s hook in Peter Pan, that they use for clambering through the branches of mosses, while aquatic species have hairy fringes on their legs that aid swimming. The aquatic species have complex life cycles, spending their early stages of development as parasites on other pond animals, and there is still much to discover about their way of life – a real research opportunity for amateur naturalists with patience and a microscope at their disposal.
To find out more about mites visit http://www.sel.barc.usda.gov/acari/frames/mites.html