Red abalone
| Red abalone | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Red abalone ( Haliotis rufescens ) |
||||||||||||
| Systematics | ||||||||||||
|
||||||||||||
| Scientific name | ||||||||||||
| Haliotis rufescens | ||||||||||||
| Swainson , 1822 |
The abalone abalone ( Haliotis rufescens ) is a species of sea snail from the abalone family ( Haliotis ). It is a relatively large species of the genus Haliotis . It is collected as a seafood in its range on the west coast of North America .
features
The case is ear-shaped and relatively flat. The individual turns increase in width very quickly, so that most of the housing consists of the last half turn. It reaches a maximum length of up to 30 cm. The outside is covered with numerous encrusting and growing organisms ( bog animals , hydrozoans , worms, algae, etc.) for camouflage . The basic color varies from whitish to greenish and brownish to red. The color depends on the diet. There are three to four openings on the top, the edges of which are raised. The used respiratory water is led out through them. The inside of the bowl is lined with a layer of mother-of-pearl . Foreign bodies are also encapsulated with mother-of-pearl, so that pearl-like structures can appear.
Geographical distribution and occurrence
The abalone is found only on the west coast of North America from Sunset Bay in Oregon to northern Baja California . The animals live with their feet attached to stones in the lower intertidal zone down to the flat subtidal .
Way of life
The animals live on stones and graze on the vegetation. The growth is very different, generally very slow. The animals take 3 to 6 years to reach a size of 10 cm. They can live to be around 20 years old. They are sexually mature after about 4 years. In the first few years only a few thousand eggs are produced, later on, depending on the size, it can be millions. Eggs and sperm can be produced all year round, with a maximum in spring and summer. They are released into the open water. Sperm and egg release are triggered by external factors, such as a sudden increase in water temperature or if the animals were exposed to the air for one to two hours. The fertilization takes place in open water. Then Veliger larvae form and live in open water for a while. They do not catch plankton , but take up amino acids dissolved in the water . After a while they sink to the ground and metamorphose . Although larger specimens would be able to cover longer distances, they are very localized on a rock or in a crevice. Here they use their feet to catch parts of plants drifting past. The color of the shell varies depending on the main food. If this consists mainly of green and brown algae , the housing is whitish to greenish. Only if the food consists of red algae to a significant extent is the casing also reddish in color.
The red abalone as a seafood
The red abalone was still very numerous on the North American west coast well into the 20th century. Due to the increase in sea otter populations and overfishing , the species has become quite rare in some areas. You also suffer from the loss of kelp forests as a result of growing sea urchin populations and rising sea temperatures. In 2017, after a sea heat wave known as "The Blob", the red abalone died out on masses, and its catch came to a complete standstill in 2018 off Oregon and California.
The populations are now being supplemented locally by small, one to two year old specimens from breeding farms . The minimum size from which specimens may be collected is 17.8 cm (7 inches). The muscular foot, which is cut into slices and prepared like a steak , is eaten .
swell
literature
- Edward F. Ricketts, Jack Calvin, Joel W. Hedgpeth: Between Pacific tides . 5th edition. Stanford University Press, Stanford, California 1988, ISBN 0-8047-1229-8 . limited preview in Google Book search
Individual evidence
- ↑ WB Jaeckle, DT Manahan: Feeding by a "nonfeeding" larva: uptake of dissolved amino acids from seawater by lecithotrophic larvae of the gastropod Haliotis rufescens. In: Marine Biology . tape 103 , 1989, pp. 87-94 , doi : 10.1007 / BF00391067 .
- ^ L. Rogers-Bennett, CA Catton: Marine heat wave and multiple stressors tip bull kelp forest to sea urchin barrens . In: Scientific Reports . October 21, 2019, doi : 10.1038 / s41598-019-51114-y .
- ↑ Ronald S. Burton, Mia J. Tegner: Enhancement of red abalone Haliotis rufescens stocks at San Miguel Island: reassessing a success story . In: Marine Ecology Progress Series . tape 202 , 2000, pp. 302-308 ( researchgate.net [PDF; 132 kB ]).
