Bald-sea-urchin Disease


Category 2 (In Canada and of Regional Concern)

Common, generally accepted names of the organism or disease agent

Bald-sea-urchin disease, red spot disease.

Scientific name or taxonomic affiliation

  1. Thought to be caused by bacteria.
  2. Bacteria identified as Vibrio anguillarum and Aeromonas salmonicida were isolated from diseased Strongylocentrotus purpuratus and used to initiate lesions on unaffected S. purpuratus in the laboratory.
  3. Gram-negative bacteria belonging to the Acinetobackter and Alcaligenes were more abundant on lesion surfaces than on healthy test surfaces.

Geographic distribution

  1. Mediterranean coast of France, Spain and Italy, and north east Atlantic coast of France (Brittany and Normandy).
  2. California.
  3. Atlantic coast of Nova Scotia.

Host species

  1. Several species of echinoids including: Paracentrotus lividus, Psammechinus microtuberculatus, Psammechinus miliaris, Arbacia lixula, Cidaris cidaris, Echinus esculentus, and Sphaerechinus granularis.
  2. Strongylocentrotus purpuratus, Strongylocentrotus franciscanus, and Allocentrotus fragilis.
  3. Strongylocentrotus droebachiensis.

Impact on the host

Associated with mass mortalities of S. franciscanus in California and P. lividus on the Mediterranean coast of France, and thought to be at least partially responsible for population declines of P. microtuberculatus off Port-Cros, France (Mediterranean Sea). This disease has also been reported in apparently healthy populations of sea urchins and among populations of S. droebachiensis undergoing mass mortalities attributed toParamoeba invadens in Nova Scotia. Althought it is considered to be a recurrent disease that in some situations may become epizootic, in many sea urchins, growth of the lesion is checked, the animals recover, and the affected areas of the test regenerate. Whether or not bacteria causing bald-sea-urchin disease may also induce echinoid mass-mortality remains to be proven.

Diagnostic techniques

Gross Observations: Characteristic lesions on the test (predominantly on oral and lateral surfaces, extending over both ambulacral and interambulacral areas except in S. purpuratus where lesions occurred exclusively in ambulacral areas) involve a central necrotic region of disorganized skeletal tissue surrounded by a ring of swollen and possibly darkly pigmented tissue. The necrotic areas are free of spines, pedicellariae and tube feet, and appear denuded.

Electron Microscopy: Lesions have extensive breakdown of the stereom and accumulation of phagocytic coelomocytes and red spherule cells.

Methods of control

No known methods of prevention or control.


Francour, P. and O. Paul. 1987. Densite, biomasse et relation taille-poids chez l'oursin Psammechinus microtuberculatus de l'herbier a Posidonia oceanica de Port-Cros (France, Mediterranee). (In French, English summary.) In: Boudouresque, C.F. (ed.) International Colloquium on Paracentrotus lividus and Edible Sea Urchins. Carry le Rouet, France, 21 Feb. 1987, pp. 169-181.

Gilles, K.W. and J.S. Pearse. 1986. Disease in sea urchins Strongylocentrotus purpuratus: experimental infection and bacterial virulence. Diseases of Aquatic Organisms 1: 105-114.

Jangoux, M. 1990. Diseases of Echinodermata. In: Kinne, O. (eds), Diseases of Marine Animals. Volume III: Introduction, Cephalopoda, Annelida, Crustacea, Chaetognatha, Echinodermata, Urochordata. Biologische Anstalt Helgoland, Hamburg, Germany, pp. 440-444.

Jangoux, M. and P. Maes. 1987. Les epizooties chez les oursins reguliers (Echinodermata). (Regular echinoid epizootics.). (In French, English summary.) In: Boudouresque, C.F. (ed.) International Colloquium on Paracentrotus lividus and Edible Sea Urchins. Carry le Rouet, France, 21 Feb. 1987, pp. 299-307.

Maes, P. and M. Jangoux. 1984. The bald-sea-urchin disease: a biopathological approach. (International Helgoland Symposium on Diseases of Marine Organisms, Helgoland (FRG), 11 September 1983). Helgoländer Meeresuntersuchungen 37: 217-224.

Maes, P., M. Jangoux and L. Fenaux. 1986. La maladie de l'"oursin chauve": Ultrastructure des lesions et caracterisation de leur pigmentation. (In French.) Ann. Inst. Oceanogr., Paris (Nouv. Ser.). 62: 37-45.

Pearse, J.S. and A.H. Hines. 1979. Expansion of an central California kelp forest following the mass mortality of sea urchins. Marine Biology 51: 83-91.

Pearse, J.S., D.P. Costa, M.B. Yellin and C.R. Agegian. 1977. Localized mass mortality of red sea urchin, Strongylocentrotus franciscanus, near Santa Cruz, California. Fishery Bulletin 75: 645-648.

Roberts-Regan, D.L., R.E. Scheibling and J.F. Jellett. 1988. Natural and experimentally induced lesions of the body wall of the sea urchin Strongylocentrotus droebachiensis. Diseases of Aquatic Organisms 5: 51-62.

Tertschnig, W.P. 1989. Impact of the "bald-sea-urchin" disease on echinoid populations of two Posidonia beds at Ischia (Gulf of Naples, Italy). (Abstract, in French.) In: Regis, M.B., A. Segui, C. Frasson, P. Escoubet, A. Riva (eds.) Proceedings of the Sixth International Symposium on Echinodermata. Echinoderms: living and fossils. Ile des Embiez-var, France, 19-22 Sept. 1988 Vol. HS, no. 10.

Citation Information

Bower, S.M. (1996): Synopsis of Infectious Diseases and Parasites of Commercially Exploited Shellfish: Bald-sea-urchin Disease.

Date last revised: September 1996
Comments to Susan Bower

Date modified: