MarLIN

information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

MarLIN Glossary

ultra-sheltered

Of wave exposure - fully enclosed coasts with a fetch measured in tens or at most a few hundred metres (from Hiscock 1990).

umbo

In the shell valve of bivalve molluscs (e.g. cockles, mussels or clams), the strongly curving dorsal region following the beak (Stachowitsch, 1992).

umbones

Plural of 'umbo'.

understorey

Organisms occurring under the main canopy of algae, especially of kelps (from Hawkins & Jones, 1992).

uniramous

Composed of a single branch, see biramous (Hayward & Ryland, 1995).

upper shore

An informal physical term for the area of the shore around the high tide level.

urchin

Rounded and covered in spines, resembling a hedgehog. Cf. sea urchin.

uropod

Sixth abdominal appendages in malacostracan crustaceans (Ruppert & Barnes, 1994). In decapod crustaceans the paired uropods may be flattened and, together with the telson, form a characteristic 'tail-fan' (adapted from Stachowitsch, 1992).

uropods

Plural of 'uropod'.

utricle

A swollen, vesicular part of the thallus of macroalgae (Hoek van den et al., 1995).

utricles

Plural of 'utricle'.