Gray sea urchin [1] , or intermediate strongylocentrotus [2] ( lat. Strongylocentrotus intermedius ) is a species of echinoderms from the class of sea urchins ( Echinoidea ). It lives in the Pacific shallow water from the southern part of the Sea of Okhotsk to the Sea of Japan. In Japan, these hedgehogs are being industrially harvested: their sex glands , erroneously called caviar , are used for food. May produce hybrids with the sea urchin Mesocentrotus nudus [3] .
Gray sea urchin | ||||||||||||||
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| Strongylocentrotus intermedius ( Agassiz , 1863) |
Content
- 1 Appearance
- 2 Life cycle
- 2.1 Reproduction
- 2.2 Development
- 3 Habitat
- 4 Power
- 5 notes
- 6 Literature
- 7 References
Appearance
The carapace of the gray sea urchin is close in shape to the ball, but is flattened from the ( oral ) pole facing the substrate. The diameter of a sexually mature individual is 30–35 mm.
In the largest specimens, the diameter of the shell reaches 8 cm, and the mass is more than 160 g. The color of the shell and needles varies widely: violet, brown, red, and green tones are described.
Life Cycle
Reproduction
With an excess of food (under experimental conditions), juveniles can reach puberty within a year after settling. However, as a rule, in natural populations the reproductive age is about two years (with a total life expectancy of 6-10 years).
Since only hedgehogs with mature sex glands are of industrial interest, in the second half of the 20th century the reproduction cycle of the gray sea urchin was studied in sufficient detail. In the course of these studies, it was revealed that spawning occurs in different parts of the range at different times. In particular, in the Sea of Okhotsk the reproductive season lasts from June to October, in the Sea of Japan it is confined to autumn, and on the ocean coast of Hokkaido , two breeding periods were discovered - spring and autumn. At the same time, juveniles resettled in other water areas retain the breeding rhythm characteristic of parents, which indicates the genetic fixation of this characteristic and the probability of isolation of populations within the species range.
Development
A bilateral-symmetric planktonic larva - echinopluteus - comes out of the egg . This stage exists for several months and is characterized by a maximum mortality rate of 75-95%. When plutus settles on a substrate, it undergoes metamorphosis : it acquires a number of new organ systems and external radial symmetry .
Habitat
Although occasionally gray sea urchins are found in thickets of sea grass and on the sandy bottom, the most typical biotope for this species is placers of stones and boulders in shallow water. In this case, young hedgehogs are concentrated among small stones (about 30 cm in diameter) and move to areas with larger ones as they grow.
The maximum recorded population density in such biotopes is 550 individuals per m². Since the beginning of the eighties, the abundance of this species in Japan has significantly decreased and does not exceed 9 ind./ m². The alleged causes are a change in hydrographic conditions and intensive fishing. Currently, gray sea urchin is abundant only in the Sea of Okhotsk.
Nutrition
Young hedgehogs feed on films of microscopic algae on the surface of stones and detritus accumulating on them. The basis of the diet of larger individuals is macrophytes, mainly brown algae . Experiments on the removal of gray sea urchins from the bottom showed that they are able to largely control the abundance of brown alga Laminaria ochotensis .
Notes
- ↑ Yavnov S.V. Atlas of echinoderms and ascidia of the Far Eastern seas of Russia / ed. V. A. Rakova. - Vladivostok: Russian Island, 2010 .-- S. 9 .-- 176 p. - 500 copies. - ISBN 978-5-93577-051-8 .
- ↑ Animal life. Volume 2. Shellfish. Echinoderms. Pogonofory. Maxillary. Semi-chord. Chordates. Arthropods. Crustaceans / ed. R.K. Pasternak, ch. ed. V. E. Sokolov . - 2nd ed. - M .: Education, 1988 .-- S. 196. - 447 p. - ISBN 5-09-000445-5
- ↑ Kafanov A.I., Pavlyuchkov V.A. ECOLOGY OF FISHING SEA HERBS OF THE GENUS STRONGYLOCENTROTUS OF THE MATERIC JAPAN-SEA COAST OF RUSSIA // Izvestiya TINRO (Pacific Scientific Fisheries Research Center). - 2001. - T. 128 , No. 1-2 . - S. 350 .
Literature
- Edible sea urchins: biology and ecology. Lawrence JM (ed.), Elsevier Science , Amsterdam, The Netherlands, 2001, 432 p. Book text on Google Books
Links
- Biology of a gray sea urchin on the website of the public organization “Club“ Boomerang “”.