By: Andrew Kiarie-Mumbi
Mollusca
Introduction To Mollusca
Mollusca are mostly aquatic and are named from a Latin word molluscus meaning "soft" due to their soft bodies that are enclosed in a hard shell made of calcium. Mollusks use sexual reproduction to pass on their genes. There is usually a male and a female with exception of snails that are hermaphroditic. Some organisms such as oysters change there sex many time throughout their life. In aquatic environments the most common form of fertilization is external, whereas fertilization in terrestrial snails is internal. The diverse nature of this phylum is also shown in many different methods of reproduction.
Mollusca are mostly aquatic and are named from a Latin word molluscus meaning "soft" due to their soft bodies that are enclosed in a hard shell made of calcium. Mollusks use sexual reproduction to pass on their genes. There is usually a male and a female with exception of snails that are hermaphroditic. Some organisms such as oysters change there sex many time throughout their life. In aquatic environments the most common form of fertilization is external, whereas fertilization in terrestrial snails is internal. The diverse nature of this phylum is also shown in many different methods of reproduction.
Caribbean Reef Octopus (Octopus Briareus)
Caribbean Reef Octopus is a coral reef marine animal. It lives in warm water, grassy and rocky sea beds. They reproduce sexually and they do not undergo any sex change during development. Male caribbean true octopus leave their dens during the day to look for a mating partner. Once they found a female they climb on top begging with some types of courtship then start the mating which last up to 80 minutes. The males dies shortly after the mating process. After they have the sperms in them females can store them for up to 100 days in their oviducts. Before laying them, they find a suitable place which will provide protection and stays their with the eggs until they are hatched. The female lays up to 500 hundred eggs which takes about 65 days to hatch but the can hatch even faster depending on the water's temperature. The newborn octopuses are able to swim, feed, and change color as soon as the are born. Their growth is very quick and they are full matured and developed within 17 weeks. Male Caribbean Reef Octopuses are sexually matured faster than females in just 140 days and females 150-160 days.
True Oyster (Ostridae)
True oyster include of the most consumed of its species. True oysters live deep in the ocean and they are flat with roundish shells.
Few of the True oysters are hermaphrodites. This mean that they fertilize their eggs within their bodies and stays there until a larva is formed and then released in the water. Most true oysters, they female discharge the egg in the water where sperms from male true oysters fertilize them. The larvae develops quickly in about six hours, swim for three or two weeks then settle on stones or shells. The larvae are fully matured by the end of their first year.
Few of the True oysters are hermaphrodites. This mean that they fertilize their eggs within their bodies and stays there until a larva is formed and then released in the water. Most true oysters, they female discharge the egg in the water where sperms from male true oysters fertilize them. The larvae develops quickly in about six hours, swim for three or two weeks then settle on stones or shells. The larvae are fully matured by the end of their first year.
Garden Snail (Helix Aspersa)
Garden snail is the most well known of its species. Just like all the other terrestrial snails, it's a gastropod mollusk. Garden snails are native to Europe, but they were introduced to other parts of the world where they became pest for garden's crops.
Like all other gastropod mollusk, snails are hermaphrodite which mean that they have both male and female organs. However, mating is required in for fertilization in snails. Snail's mating process begin with some type of courtship which may last from four to twelve hours. After fertilizing each other, snails take 3 to 6 days to lay over 80 eggs. These eggs are laid in a nest which is dug in the soil. The nest is about 1 to 2 inches deep.. After hatching, the newborn garden snail take up to 2 years to fully mature.
Like all other gastropod mollusk, snails are hermaphrodite which mean that they have both male and female organs. However, mating is required in for fertilization in snails. Snail's mating process begin with some type of courtship which may last from four to twelve hours. After fertilizing each other, snails take 3 to 6 days to lay over 80 eggs. These eggs are laid in a nest which is dug in the soil. The nest is about 1 to 2 inches deep.. After hatching, the newborn garden snail take up to 2 years to fully mature.