Behaviour

The behaviour of Agalma elegans alternates between:

  • passive drifting
  • active swimming, which maintains the position of the siphonophore in the water and enables it to find food

Once in a suitable location:

  1. The animal relaxes.
  2. The stem drifts into arcs above the nectosome (of swimming bells).
  3. The tentacles extend.
  4. Side branches of the tentacles also extend and spread out the orange-red tentilla into a feeding net. This feeding net is almost invisible in the water, with only the coloured tentilla visible to potential prey.

How do Agalma species catch prey and feed?

  1. Species of Agalma may actually jiggle the tentilla up and down slightly to mimic a swimming copepod or other small zooplankton, attracting prey to the tentilla. 
  2. Prey becomes ensnared by the long transparent terminal filaments.
  3. As the prey struggles to escape, the cnidoband of many nematocysts (17,030 per band in A. elegans) is slapped onto it and toxins are injected, immobilising the prey. 
  4. The tentacles contract, bringing the prey to the mouth. 
  5. The mouth envelops the prey, pours enzymes onto it and digestion begins.
  • An oceanic filefish of the family Monacanthidae
    Associations

    Find out about the predators and parasites associated with Agalma elegans.