HOW DO SNAILS REPRODUCE ?

     >>By Mohamad Khairi .B. Mohd Adenan

Snails will be able to reproduce differently than almost any other type of creature because of their species and their make-up. 

There’s 2 types of  Snails:

- Hermaphrodites (every snail will have both male and female reproductive organs.)  Examples include land and marine species. 

- Dioecious ( having the male and female organs in separate and distinct individuals; having separate sexes.)
Examples include (apple, golden inca, four horned, etc.)

There are also 2 different types of fertilisation : 

 - Internal fertilisation(copulation) 

 - External fertilisation (externally in the water). 

(internal fertilisation)

Snails are hermaphrodites, with both male and female sexual organs in the same body. A penis is extruded from the side of each head as the snails join together.

 

 

(Dioecious)(External Fertilisation in the water.)

The sperms and eggs are released into the water and fertilisation occurs.

              Snails are considered sexually mature when they reached a year old, as the lifespan of most species does not last for more than about 5 -7 years. This allows for a faster growth rate of the species.  The make-up of the snails will include their reproductive organs on the side of their body.  This is close to the top of their body as well, allowing for easier abilities to mate and to grow the baby snails. 

              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, going through a complete mating ritual with each other, usually copulating with the other snail for an average of two to twelve hours. Snail copulation is actually an exchange of sperm between two individuals, combined with plenty of rubbing, biting and 'eye-stalk' waving. Snails use the received sperm to fertilize their own eggs at the end of the copulation. 

              She will usually continue about her life, walking around the tank while the male continues his deed riding on her shell. It is known that a snail can carry up to 100 eggs at a time. Females may or may not lay eggs after the male breeds her. Pomacea species snails can carry sperm in their bodies for many weeks.

              Most snails lay eggs but some, like the trapdoor snail, give live birth. Trapdoor snails and a few other species of snails such as (apple, golden inca, four horned, etc.) are not hermaphrodites. They can only reproduce sexually.

               
              Some snail species make 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). 




Websites:


http://www.artsaquaticsandanimals.com/


http://www.snail-world.com/How-do-Snails-Reproduce.html


http://www.wikipedia.org/


http://www.applesnail.net/content/anatomy/reproduction.php






Pictures from Yahoo and Google search engines.












                                          :)(:  REFLECTION  :)(:


            I have always wondered how snails reproduce, and I am really glad I had this as my e-learning assignment. Thank you Ms Nada! Without this assignment, I would never have been moved to find out about snail reproduction.


        
            I find snails quite a unique species, and after the research about them, my appreciation to them grew even more. I would be much more careful not to step on snails the next time. The way in which they reproduce quite amazes me, with their " love darts " and how the male crawl up the female's shell and does the "deed". I was also amazed at 
the picture of the snails (internal fertilisation) where they coil their sexual organs. Indeed,I have found out much more about snails than I've used to know. They are 2 types of snails,  hermaphrodites and dioecious, and 2 ways in which they reproduce, namely external and internal fertilisation. 




             We have to understand and try to appreciate each and every single species that have been created by god, as how we try to understand and appreciate other cultures, traditions and races. Each species is unique in its own way. Even if we don't like it, we must still respect it. Criticising the species is like critising  god's creation. Everything is there or done for a reason. Snails also belong to food webs, pets of many children and unfortunately in my opinion, delicacies in some countries like France. 




             Whatever it is, without the existence of snails, our world would be " a species less exciting. "

Reproduction of snails-- by Muhan

Snails will be able to reproduce differently than almost any other type of creature because of their species and their make-up. This begins with the build that all snails have.


Snails are considered to be hermaphrodites. This means that every snail will have both male and female reproductive organs. This is especially consistent among land snails and most marine snails.

The only snails that have not adapted this attribute are some freshwater and marine species, specifically including Apple Snails and periwinkles. These two types of snails still have a separate male and female species and are called Dioecious.

All snails will be considered sexually mature by the time they are one year old. This is because the life span of most species does not last for more than five to seven years, allowing for a faster growth rate of the species.

Structure of snails

Reproduction

hermaphrodites:

Common snails, like all land snails, are hermaphrodites. This means that they possess both male and female reproductive organs. Despite this they still need to find another snail to mate with. When two snails meet during the breeding season (late spring or early summer), mating is initiated by one snail piercing the skin of the other snail with a calcified 'love dart'. The exact purpose of the 'love dart' is not fully understood but it seems to stimulate the other snail into exchanging small packets of sperm. After mating is complete the snails will produce eggs internally, which are fertilised by the sperm that has been exchanged.


Up to about a month after mating the snail lays about a hundred small white eggs in a nest underground in damp soil. If the conditions remain suitable for the eggs, snails will begin to hatch after about 14 days. Newly hatched snails have a small fragile shell and it takes two years for them to reach maturity.

love dart of the snail

Reproduction

Dioecious.

Usually takes place in water.

Male reproductive system:


During mating activities, this penial papilla bends towards the sperm groove in which the sperm is conducted. From this sperm groove the sperm is conveyed in the penial duct at the base of the penis.

The penis itself is coiled in a basal pouch (penial sac) when not used. On erection the penis comes out of the penial sac and is grasped around on the lower thirth by a muscular penial sheath from the mantle. It's the latter, which can be seen when the snails are mating. The real penis is rather thin, whip-like and often stays out of sight.

Female reproduction system:

The egg cells of the female snail are stored in the ovaria, which are located in the top of the spine, closely to the digestive gland.

Male at the left inserts his penis in the female.

Close up of the picture at the left, with the penis sheat inserted in the female snail.

Normally the penis sheat is folded inside the mantle cavity, but sometimes it folded outwards and visible.

Reflection

I'd taken some snails home and fed them once last year only because I found they were fun to play with. I put the box which had snails in on my bookshelf, and as a result, my chemistry assignment book ended being eaten up several pages.  That incident irritated me very badly, so I threw these snails out of my house.

At that moment of time I thought they were only stupid soft animals moving aimlessly, and they carried their heavy "houses" (shell) wherever they went to.

But after finishing the research about the snails, I changed my mind as I'd realised that they actually had their own greatness. Their organs are so specialised and each of them is unique, working to serve their respective purposes. They possess specially designed "love dart" for their mates to touch as triggers as if they are small caring machines who'd considered a lot to change their body structures just to make their mates feel convenient. Wow, the nature is just so amazing for creating so many creatures like them.

Some dioecious snails release their sperms and eggs into water, making fertilisation can only occur by chance. That is undoutedly a tough job for snails to do, but they manage to make it and each of them contribute its own power to prevent the extinction of their species from happening. We all know how slow a snail moves, it must be traveling a extremely long distance to meet its mate. Some probably even have to fight against the currents of river to survive and get themselves fertilised.

The story of snails is very impressive, now I've learnt to respect and appreciate the nature. I think every living organism must have its own value and reason to be here. As the masterpieces of our mother earth, we are all equally great.

How do snail Reproduce?*from Chor Kia Kwee

Two types of snail

a) Hermaphrodites
A snail which has both male and female reproductive organs.
For example, land snails and most marine snails.

b) Dioecious
A snail has separated sexes
For example, Apple Snails,freshwater and marine species.

Anatomy of a snail

Fertilisation
a)External fertilisation

Dioecious

Fertilisation takes place externally in the water.
Eg. Archaic prosobranch snails (Patellogastropoda).
Sperm and egg cells are released into the water and fertilisation occurs by chance.

b)Internal fertilisation
Hermaphrodites

Land snail
During courtship, each snail manoeuvres to get its genital pore in the best position, close to the other snail's body. Then, when the body of one snail touches the other snail's genital pore, it triggers the firing of the “love dart”.

S-dart sac, D-love dart,P-penis

Love darts are used as part of the sequence of events during courtship before actual mating takes place.

During mating, both penises are entwined and inserted into the mate's vagina.

                                     Can you see the dart of the snail on the left?

Each snail would stimulate the other snail into exchanging small packets of sperm..

After mating is complete sperm packet, called spermatophore, is produced in either snail's body and afterwards filled with sperm cells.
The snails will then produce eggs internally, which are fertilised by the sperm that has been exchanged.
Up to about a month after mating the snail lays about a hundred small white eggs in a nest


The advantage of an internal fertilisation

The eggs are provided with additional nutritive cells (yolk) as well as with protective coats inside the snail, such as egg shells (terrestrial snails) or egg capsules (many sea snails, such as the whelk).

A snail can carry up to 100 eggs at a time.

It lays eggs and buries them into a cool place.
 For land snails, they will be buried underneath the dirt in order to be cared for. With marine snails, the eggs will be placed next to a solid area, such as a rock.
This will allow the eggs to stay in the same place and develop without being harmed.


A snail egg two to four weeks in order to develop.
They hatch by either eating their own egg or eating other eggs in order to get the extra nutrients. It will take around three months for the snails to completely form. While this takes place, they will stay in a nest that has been built for them, with the transformations being seen through a change in color, from a clear colour into blue then into the adult form that is representative of the species.

Question:
How do snails find a mate?

The method used is slime trail following.

Reflection
           How many times have we passed by a snail without noticing its existence?In life, we are too oblivious to our surroundings and the beauty of nature that seldom does one ponder how this small and soft animal make its living.

        
           Through this research, I was awestruck by the incredible organ make-ups of the snails. I become more appreciative that every organism is unique and gain insights that every organ serves its own purpose for the survival of an organism.

         
            Besides that, it deeply provides me food for thought.A snail, no matter how slow, would still complete its journey in order to accomplish its objective which is to find its mate. I was captured and intrigued by the determination of the snail. It works single-mindedly and has invincible belief in its own ability towards its goal.
  
    
          "Sometimes in life,we're moving slow...
                 There’s nothing wrong moving on a snail’s pace...
                        Slow and steady running its own race...
                            And it knows where the finishing line is...__"
                                                                             ~Kia Kwee

How snails reproduce!(By Han yi)

Most snails are hermaphrodites-both male and female. All hermaphroditic snails can lay eggs. They can "mate" with themselves and thus only one can reproduce in an aquarium or pond. They also breed sexually as often as possible. Most snails lay eggs but some give live birth.

Snails will be able to reproduce differently than almost any other type of creature because of their species and their make-up.

All snails will be considered sexually mature by the time they are one year old.  This is because the life span of most species does not last for more than five to seven years, allowing for a faster growth rate of the species.

Snails will go through a complete mating ritual with each other, usually which will communicate to the other snail for an average of two to twelve hours.  At the end of this ritual, the pair will fertilize the eggs in the other.  It is known that a snail can carry up to 100 eggs at a time.

When the eggs are fertilized, they will go through a process of growth inside the snail.  This begins with the fertilization moving the snails into a specific amount of development inside the embryo.  This takes place with the snails laying eggs and burying them into a cool place in order to develop.

For land snails, they will be buried underneath the dirt in order to be cared for.  With marine snails, the eggs will be placed next to a solid area, such as a rock.  This will allow the eggs to stay in the same place and develop without being harmed.

The young snails hatch after a few days and then start to breed very quickly.

It will typically take a snail egg two to four weeks in order to develop.

Reflection
At first, I did not ever wonder how does some animals reproduce such as snails, but after this research, I have found out about snails' reproduction. I feel intrigued about this and I have decided to find out more on some of my favorite animals.

Other than the reproductive system of snails, I've found out more on the snails. All snails are classified as mollusks because of the hard shell that protects their bodies. Many people confuse slugs as snails but they aren’t in the same category due to the fact that they don’t have shells.


This assignment makes me feel like I am out of the textbook and I think we can learn more general knowledge through this kind of research. This is one of the many times that I feel Biology is a very lively lesson, not just stuck in the textbook.

Thanks to Ms Nada for helping me to be back to my interest on Biology.

YouTube - FLOWERS IN GROWTH (TIME LAPSE)

YouTube - FLOWERS IN GROWTH (TIME LAPSE)

Reflection

It was a wholesome pleasure to have visited Singapore Botanic Garden. We have learnt many things which are beyond our limited textbooks through this trip. We were intrigued by the nature and the structures of exotic flowers and wanted to find more about them. Halfway through the journey, our enthusiasm got the better of us, we ventured deeper into the botanic garden. We felt invigorated at the breathtaking view of the botanbic garden. Despite the hot weather, we perservered on and let our enthusiasm drove us around the Botanic Garden. After the trip, we have realised that the importance of the symbiosis relationship between us and the plants. We need to depend on each other for survival. Therefore, it is significant for us to preserve and appreciate the plants in the botanic garden, so that the botanic garden will be well-protected for our future generations.

Last but not least,we felt very fortunate to be given this precious opportunity to visit the Singapore Botanic Garden. We got to know the chapter in an interesting and interactive way. The trip was probably one of the most wonderful memmories in our secondary school life. We certainly hope for more such trips to be organised in the future.