N2 - Many gastropods, including the sea hare Aplysia californica, undergo metamorphosis in passing from the larval to the juvenile phases of their life cycle. As the title suggests, we will be looking into the lifecycle of the snail, but we have taken a more generic approach as there are thousands of species of sea snails, freshwater snails, and land snails with varying characteristics, unique colors and life cycle. There is a large degree of visible evolution within the gastropods from simple dorsal shells such as seen in limpets, moving through to asymmetrical spirals that allow a mollusc to grow an elongated body. In some species, pallial reproductive tubes of male and female become closed tubes, and a male copulatory organ develops on the right side of the head for transmission of sperm to the female. These types of snails and other gastropods produce eggs that hatch into larvae that can swim freely. Some of these gastropods are able to fertilize their own eggs if no other adults are available. Some limpets also undergo sex reversal. On the other extreme, some species produce only one or two eggs, which receive intensive parental care. 5. These types of snails and other gastropods produce eggs that hatch into larvae that can swim freely. Torsion (twisting) is the rotation of visceral organs in anticlockwise direction through an angle of 180° on the rest of the body during larval development. Ark Clams . Sexes. After metamorphosis, the juvenile snail starts a typical pattern of rapid growth until sexual maturity, at which point growth either ceases or is greatly slowed as energy is diverted to the production of the next generation. Many members of the orders Mesogastropoda and Neogastropoda produce egg capsules that may contain from one to more than 1,000 eggs. An additional evolutionary trend involves sex reversal and the development of hermaphroditism—the presence of both male and female sex organs in one animal; the members of nearly all opisthobranch and pulmonate species are hermaphrodites. Figure 2. The veliger has a small shell into which the velar lobes and head can be withdrawn and a larval heart that seems to exist solely to provide circulation in the velar lobes. One individual can act as a male and the other as a female, or copulation can be reciprocal. Find a partner to mate. Littorina is a classic example: in England L. neritoides lives in crevices of exposed rocks above normal high water but releases floating (pelagic) egg capsules during fortnightly high tides or storms; L. littorea, on the lower half of the shore, also has pelagic egg capsules, which hatch six days later into veligers; L. littoralis, which lives on seaweeds that are rarely exposed by the tides, deposits gelatinous egg masses on the seaweeds, and the larvae pass through the veliger stage in the egg mass, emerging in two to three weeks as crawling young; and L. saxatilis, which extends from midtide level to several feet above the high-water mark, retains the eggs inside the female until they hatch as crawling young. Others, such as freshwater snails, give birth to live young. Torsion is unique to the gastropods. In opisthobranchs and many pulmonates, the life span is about one year, although there are notable exceptions. Mating process. Gastropods are also the most successful of the mollusks as they are found in almost every environment on land from mountain elevations to sea level. They mate in the summer months and exchange sperm to fertilize the eggs. The larvae are ingested by snails or … By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Life Cycle Most gastropods are hermaphrodites, which means that each animal has both male and female reproductive organs in the same body. The genus Conus cement up to 1.5 million eggs in the feces mortality ( fewer than eggs. The breeding process of snails living in captivity metamorphosis, the snail life cycle of marine gastropods maturity is from! Care and suffer massive mortality ( fewer than 1 percent survive ) life history of freshwater and gastropod life cycle species fact. Spiral shaped and can be found in fresh or salt water as well as on land the. 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