Escape responses of gregarious mysids (Crustacea: Mysidacea): towards a general classification of escape responses in aggregated crustaceans

• Published in: Journal of experimental marine biology and ecology 1988-01, Vol.116 (3), p.257-272
• Main Authors: O'Brien, D.P., Ritz, D.A.
• Format: Article
• Language: English
• Subjects: Aggregation; Animal ethology; Avoidance; Biological and medical sciences; Crustacean; Escape; Ethology; Fundamental and applied biological sciences. Psychology; Marine; Mysid; Mysidacea; Protozoa. Invertebrata; Psychology. Psychoanalysis. Psychiatry
• ISSN: 0022-0981; 1879-1697
• DOI: 10.1016/0022-0981(88)90031-7

Escape responses of a range of schooling/swarming crustaceans both from the literature and from our own observations of Paramesopodopsis rufa Fenton, (1985), Tenagomysis sp., Doxomysis sp., and Anisomysis mixta-australis (Zimmer, (1918)) (Mysidacea) from southeastern Tasmania are examined. The wider applicability of the scheme proposed for classifying escape responses of euphausiids was demonstrated. This is despite the fact that the hyperbenthic mysids chosen showed varying degrees of attraction to the substratum. Three levels of response are proposed for both pelagic and hyperbenthic crustaceans. (1) Primary response. School detects predator out of striking range and avoids threat by moving out of the predator's field of perception. Normal swimming mode and school cohesion are maintained. Mechanisms of concealment from the predator, such as camouflage, which aid detection of the predator prior to it detecting the prey, are included in this category. (2) Secondary response. Predator within striking range causes a coordinated reaction of whole or part of the school, usually manifested by an increase in swimming speed of the individuals nearest to the predator; larger schools may split. (3) Tertiary response. Predator attacks causing a fright response at the individual level resulting in the breakdown of school cohesion. Escape is usually protean in nature, involving leaps or jerks, i.e., tail flips. In each case, the aggregative state of the prey interacts with predator size and distance. Substratum relations also influence the escape in hyperbenthic species. This array of responses is comparable in complexity to that seen in schooling fishes and strongly suggests that this behaviour has coevolved with the form and foraging behaviour of the predator. Finally, the extension of the scheme to cover gregarious crustaceans as a whole is discussed.