In situ behavioural studies on echinoderm aggregations
© Biologischen Anstalt Helgoland 1973
1. On the west coast of Ireland, a number of echinoderm species have been found to exhibit extreme aggregation. Population densities for some of these animals are amongst the highest on record.
2. Detailed studies have been carried out on aggregations of the holothurianPseudocucumis mixta Östergren. These provided information on habitat preference, mode of burrowing, method of feeding and the animal's sensitivity.
3. In situ observation established the existence of a diurnal feeding rhythm which may be primarily controlled by light.
4. The manner of defecation and the nature of the faeces would appear to rule out self-fouling by the aggregation.