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Monday, April 5, 2010

Bio E-learning (mervyn)

here is my post for the assignment for Biology,

mervyn here, i do wonder how snails reproduce but i have never actually go into the subject and dig for information but when given this assignment, i have actually found out that most snails are actually hermaphrodites i dont know how to pronounce hermaphrodites but i understand that hermaphrodites have both female and male sexual organs.

snails are hermaphrodites but they do not fertilize themselves but instead they find mates which they will encounter throughout their lives, there was one site where they said that snails mate with every snails of their kind which they meet and that both snails will be fertilized. i also noticed a paragraph which they state that only one or two species of snails have only one sexual organ, the Pomacea Bridgesii for example, they are not asexual where a male and female are requird for fertilization, the male would place his sperm in the female shell and would continue to hold on onto the female's snail shell. the sperm would last a few weeks in the female snails shell.

its a wonder how a snail would live everyday. the infomation below is the combination of two websites information. i have learnt many facts about the snails and i wnder if there would be any other animals which will be as mysterious as the snails.



http://www.snail-world.com/How-do-Snails-Reproduce.html
http://wiki.answers.com/Q/How_do_snails_reproduce
http://answers.yahoo.com/question/index?qid=20061010073700AAxifWT
and theres one more but the website wasn't found.









Snail reproduction is a curious tale. Snails are hermaphrodites, but although individuals contain both male and female sex organs, they do not self-fertilize. The two to six hour marathon session that is snail copulation is actually an exchange of sperm between two individuals, combined with plenty of rubbing, biting and 'eye-stalk' waving. Individuals use the received sperm to fertilize their own eggs — a process that is necessary to maintain genetic diversity in the population.

What makes some snail species particularly interesting to Dr. Chase is their use of 'love darts' during copulation. About one third of snail species manufacture hard, sharp darts which they 'fire' at the object of their affections (i.e. other snails).

"The love dart phenomenon has been documented in the literature as far back as the mid-17th century," noted Dr. Chase. "Love dart snails were known to the ancient Greeks, and it wouldn't be surprising to find that they influenced the creation of the cupid myth".

Dr. Chase became intrigued with snails' 'love darts.'

"It was incorrectly believed that these darts were a nuptial gift of calcium —a major constituent of snail shells—from one snail to another. Like a bunch of flowers or a box of chocolates in humans," explained Dr. Chase. "Another belief was that the dart was intended to arouse the receiver and indicate the shooters readiness to mate."

Research conducted by Dr. Chase has uncovered the real reason for dart shooting in snails, and the truth is much more sinister than previously thought.

The answer lies in Darwin's theory of sexual selection. Basically, snails want to reproduce as much as possible. Snails that have a way of ensuring that their sperm, rather than another's, is used to fertilize eggs will therefore sire more offspring. This is known as sperm competition



All hermaphroditic snails can lay eggs. Tim can "mate" with himself and thus only one can reproduce in an aquarium or pond. he also breeds sexually as often as possible. Most snails lay eggs but some, like the trapdoor snail, give live birth. Trapdoor snails and a few other species of snails (apple, golden inca, four horned, etc.) are not hermaphrodites. They can only reproduce sexually.
Underwater Snail Eggs: For those snails that lay eggs in the water, snail eggs look like little jely blobs stuck on hard surfaces and plants. Favorite places to lay eggs include aquarium glass, clay pots, bricks, large plant leaves, and almost anywhere sturdy enough. The eggs begin clear but soon get a dark spot which grows larger as the snails grow. Unlike fish eggs, you will not see two large eyes looking up to you. After about 3-6 weeks depending on species and temperature, the babies emerge. They are quite vulnerable to being eaten at that time. There is nothing special to be done for their care aside from providing foods their parents like if algae and plants are scarce. People often add snail eggs to aquarium and ponds without knowing it as the eggs come hitching rides on live plants or even inert materials moved from another aquarium or pond. Rarely, eggs may be infertile or die. In that case, they will turn white as fungus attacks them. Healthy snail eggs are clear with a dot inside.
Above Water Snail Eggs: Apple snails lay eggs above the water line, usually on plants but in an aquarium, they often lay eggs on the lid. Apple snail eggs are yellow or pink. They need to stay damp but not submerged in order to develop.

Mystery Snails are most likely a species called Pomacea Bridgesii. These are freshwater aquatic snails which lay eggs ABOVE the water.
Pomacea snails are MALE and FEMALE. They are NOT aesexual. So you will have to have 1 male and 1 female, at least, before you see breeding and egg laying.
The male will climb onto the females shell, slightly over to one side, his penis looks like a flat white tube (similar to his breathing siphon, but shorter and fatter) and he will insert it into the female's shell and up into her body.
She will usually continue about her life, walking around the tank while the male continues his deed riding on her shell.
Females may or may not lay eggs after the male breeds her. Pomacea species snails can carry sperm in their bodies for many weeks.
When ready to lay eggs, the female will climb up the side of the aquarium wall and leave the water. She will continue up as far as she can go, or about 3-4 inches.. depending on how much room she has. If you do not have a lid on your aquarium, she can and most likely will, fall out of the tank.
My snails enjoy laying their eggs near the light bulbs in the light canopy. The eggs are a small hard mass, usually pale creme in color. Though some other Pomacea species lay bright red, dark pink, lime green, and solid white eggs.
If eggs are kept warm and moist, baby snails will hatch on their own in about 2-3 weeks. Sooner if they are kept warmer. Baby snails will eat their way out of their egg cluster and drop down into the water. They look just like their parents, only tiny. It takes some color-varieties a few weeks before they show their adult coloring, but wild- and golden-colored babies look pretty much like their parents from day 1.
Sometimes the eggs won't hatch. This is usually due to lack of humidity, though sometimes a virgin snail can lay eggs which are infertile. Usually if you leave the eggs alone, and let nature take it's course, you will soon have alot of babies in your tank.
One single egg clutch can hold anywhere from 20 to 2,000 eggs depending on the species. Asolene Spixi, which is a rare forum of apple snail, usually lay egg clusters that only have 15-20 eggs. Pomacea Canaliculata can lay clusters with up to 2,000 eggs.

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