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Abalone

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Abalone
Red abalone.jpg
Scientific Classification
Species

The abalone is a marine snail from the phylum Gastropoda. Also, being a member of the genus Haliotis, which means "sea ear". It perfectly describes the shell because it is flat and spiral shaped. They are most famous for their beautiful iridescent shells, and can grow to be large and live long lives. [1]

A popular disease among the abalone is the withering syndrome. The withering syndrome causes the foot of the abalone to waste away and become shriveled and useless. In an organism with a high case, it wouldn't be able to move well, which would eventually lead to the animal's death. This disease is a highly contagious, bacterial infection and is spread through feces that gets ingested by other organisms. It is caused by a rickettsia-like pathogen. The black abalones are the ones that seem to be most affected by this. But both wild and farmed are vulnerable to this which concerns the farmers and scientists greatly. On the upside, a University of Washington professor, with the help of a California college, came up with a cure that is up to 90% effective.[2]

Anatomy

This is the inside of an abalone shell; see the iridescent layer

The abalone's shell contains respiratory pores along the outer spiral of its shell. These are used for bringing in water, and also for excreting waste. After the water circulates throughout the system, such as the gills, the bodily wastes come out with the current.[3]Although the outside of the shell may not look very appealing, the inside of the shell is made up of nacre, known more commonly as "mother-of-pearl". This causes the shell to have an iridescent tint providing it with many magnificent colors. [4]

The abalone also has a muscular foot that makes up the visible, underside of its shell. Along this foot the epipodium is the part that comes out under the shell and provides means of sensory and they also contain small tentacles. The epipodium is also the best way to decipher the different species apart from one another. The species have a variety of textures, from smooth to bumpy, and appearances. They have a mouth and radula that scrape off algae to be eaten for food. Instead of having a brain for the nervous system, they have ganglia grouped together in the head that run throughout the body and provide the necessities it needs. Like most other Gastropods, they have an open circulatory system. Their blood circulates through arteries, veins, and sinuses with aid from a simple heart. [5] They also have a pair of eyes connected to their heads; they stick out on the very edge of the shell. The largest organ that the abalone holds inside its shell is the gonad (digestive system organ). If the gonad is a green or grey color the abalone is a female, but if it is a cream color it is a male.[6]

Reproduction

Most abalone are dioecious (separate sexes), although there have been a few hermaphrodites (both sexes) found. [7] The reproduction time of an abalone is all dependent upon their environment. Spawning is during the summer months, from April to August. [8] But it also depends on the water temperatures, extreme weather conditions, photoperiod (length of day), and the lunar cycle. When it's time, the female releases eggs through their respiratory pores, on the top of their shells. Once the females release, it triggers the males to also release their sperm, also through the pores. Fertilization takes place in the water columns. When the larvae first start out they are able to swim and find a good living habitat, but once they've found good ground, they loose their ability to swim. Although few survive the first couple months of living, those who do have the opportunity to live very long lives, up to 50 years old. [9]

During the first day following fertilization a blastula and a trochophore (only Archeogastropods) develops. [10] After the first day, they develop into veliger larvae. A few weeks later the larvae will settle, this process is called a "spat". Once the abalone is 2-3 years old it has reached full maturity and becomes an adult.[11]

Ecology

Some abalone, like the northern abalone, live in open, rocky shorelines. Depending on the different species the depth of their habitat in the ocean may vary exponentially. In order for their survival they must live in a habitat with high levels of salinity, salty water, and low temperatures. They live in aggregations, or groups. Although they are motile animals they don't travel far throughout their life span. While the young abalone will usually be found in the Nereocystis kelp beds, the older adults would be found in the macroalgae. Abalone are herbivores, they eat kelp, phytoplankton, and diatoms. Some of the predators of the abalone are the octopus, crab, lobster, seastar, and otter. [12] Specifically, the eggs are eaten by filter feeders, the young abalone are eaten by crabs, octopi, starfish, and fish, and the adults are eaten by large fish and octopi. They can live exceptionally long lives up to 50 years. [13] But it takes them an especially long time to grow and must avoid becoming prey to other animals.

Different species of abalone can be found from the inter tidal zone to depths of 165 meters (540 feet).

Human Uses

The abalone is used for many different human resources. The inside of the shell is used for jewelry and in guitars because of it's iridescent layer of nacre. The inner meat is a delicacy in many places around the world, mostly in Asia. Such as in Japan, for high quality abalone it is expensive and a real treat when one gets the opportunity to eat it. Because of their popularity they are being farmed everywhere, especially in the U.S..[14] Sometimes the abalone even produces a pearl inside of its gonad, like that of an oyster.[15]

Gallery

Related References