Mature individuals typically measure 30-100cm long.
A. elegans has a flexible body which is composed of 3 main areas:
The pneumatophore is a small gas-filled float at the extreme anterior end of the animal.
In Agalma elegans, this float has:
Next to the pneumatophore at the anterior end, the animal has a series of swimming bells (nectophores). Together, these bells form the nectosome.
The presence of a float and many swimming bells (and a long siphosome) make Agalma elegans a long-stemmed physonect siphonophore.
Contraction of the nectosac forces water out through the ostium. During swimming, all nectosacs contract together and the animal progresses forwards by jet propulsion.
The proximal surface of each nectosac is flattened in Agalma elegans and lacks the bi-lobed extensions found in the nectosacs of most other UK physonects.
Behind the nectosome is the main stem (siphosome), which is composed of up to 30 repeated units (cormidia).
In Agalma elegans, each cormidium extends along the stem and comprises:
In Agalma elegans, the tentilla comprise:
The reproductive organs are either male or female. Each cormidium contains both, but they will not become mature at the same time in any one individual.
Agalma elegans can be identified by the:
Learn which other species are also in the genus Agalma and discover how A. elegans can be distinguished from them.