how do molluscs and enchinoderms mate?

Question

they don't seem to have any reproduction organs at all!

Answer 1

Bivalve molluscs (oysters, clams, mussels, etc.) mate like fish -- that is, the female releases ova into the water as the males release spermatozoa. The ova are fertilized (or not), they gestate for a short period of time, and then larval forms of the parent species develop. Most bivalves swim freely in this larval form, at the end of which time some of them (mussels, most notably) cement themselves to a fixed object and repeat the cycle. Others (like scallops) retain the ability to move freely as adults.

Cephalopod molluscs (squid and octopus) mate in a slightly more intimate fashion. It's true that they do not have sexual organs, but the male octopus has a specially-adapted tentacle used specifically for breeding. After a tenuous and dangerous courtship (female octopi being larger and more aggressive than males), if he is successful, he reaches under his mantle and removes a sac of sperm, which fits into his specially-adapted tentacle. He then slips this sac under the female's mantle.

The female responds to this by tightening her mantle, breaking open both her sac of ova and her mate's sac of spermatozoa. The ova are fertilized, she expels them through her her siphon, and they gestate and hatch.

Sometimes, the female's response is violent enough that the male's tentacle is ripped off (reminds me of an old girlfriend... sorry. :-) This has led to reports of "nine-legged octopus" swimming in the ocean. And while I'm sure it doesn't do the male any good, cephalopods can regenerate lost limbs, and it's better than the fate that befalls an unlucky male praying mantis.

Squid mate in much the same way. I have, while cleaning squid for a meal, discovered the sacs of gametes inside the respective mantles of female and male squid. I don't know how to tell squid apart from the outside, but it was immediately apparent on, er, "dismantling" the squid.

Both octopi and squids have complicated, sometimes intricate mating rituals. With octopi, it's a sort of combination between a dance and a massage; the male essentially has to convince the female that he's neither a threat nor a meal, and he does this by waving his tentacles and gently caressing her. Squid do something similar, but with a twist that is occasionally beautiful to watch: most squid have chromatophores (that is, color-bearing cells) in their skin, and can flash them in beautiful patterns and colors, sometimes breathtakingly quickly. The cuttlefish (a squid with a particularly osseous pen) changes colors several times per second, and is just stunning to watch. The patterns seem to convey some kind of meaning between male and female, however, and after sufficient meaning is exhanged, the mating is consummated.

Land molluscs are downright nasty (and fans of Monty Python may now join me in saying, "The whelk is a right whore..."). Snails are androgynous, and form mating clusters in which a single individual may simultaneously be impregnating a second while being impregnated by a third.

Echinoderms also have "free-range" sex: the females release their eggs and the males release their sperm and everybody hopes for the best. Note that much of the biomass that we think of as plankton is actually made up of the floating embryos of molluscs and other sea life. The reproductive strategy of animals that mate this way is basically to release as many potential offspring as possible, in the hope that enough of them will survive to adulthood that the species will survive and, if possible, flourish.

I *will* say that the ova of the common sea urchin can be very flavorful, but only when I've eaten them in Japan. Known as uni, sea urchin roe is a vibrant ocher yellow, slightly sweet and with an odd texture. California uni is significantly less pleasant than Japanese uni; whether this is due to species differences on opposite sides of the Pacific, due to a sort of oceanic equivalent of what the French call "gout de terroir" (flavor of the soil) in winemaking, or due to freshness and quality of the Japanese product versus that in California, I do not know.

If you are interested in learning more about the mating habits of living things (and who isn't? :-), check out the book included in the Sources frame, available on Amazon.com. Titled "How They Do It," it is a review of the reproductive details and sexual habits of some 47 different species, from snails and octopi to rabbits, bedbugs (the females have no vagina) and porcupines (with quite a bit more information than "very carefully").

Personally, I think the book would make an awesome Animal Planet special, hosted by Nigel Marven... or Steve Irwin. "Crikey! Look at the tentacles on that little ripper! Isn't she a beauty!"

Answer 2

Mollusca

In some other species like the “prosobranch” snail, both have 2 sexes and reproduction occurs by spraying the eggs and sperm into the water but fertilization may happen or not and it’s a matter of chance.
How do organisms in the phylum mollusca reproduce is unique and during the ejection of eggs and sperm cells into the water there is some form of chemical agents that stimulate other mussels to spawn or generate their sperms and eggs.

Fresh water mussels are quite different that the sea mussels as the larval stage lives parasitically within fish's tissues, gills or fins for about 2 weeks until they detach, and independently live on their own and sink down to settle to the substrate. This behavior of reproduction is one of the strategies for mussels to spread their larvae in order to colonize new mussel beds.

How do organisms in the phylum mollusca reproduce? Reproduction for other classes of molluscan can be sexual and this happens to snails. Common land snails are also hermaphroditic. They have both male and female reproductive organs snails and can mate mutually but still they prefer find another snail to mate with. Mating happens also during some particular time and temperature and usually during late spring or early summer. One snail stabs the skin of the other snail with what they call a calcified 'love dart' to stimulate the other snail and the sperm is transferred or exchanged from one to another sexual partner. Female snail will then produce eggs internally and then fertilized by the sperm that has been exchanged. It takes around 1 month for the snail to lay eggs, 14 days to hatch and 2 years fro the baby snails to become mature.

How do organisms in the phylum mollusca reproduce? The reproduction the squid starts when a male squid produces a special arm called a hectocotylus that transfers male sperm to the female squid through her pallial cavity. Once fertilized the female later lays a number of eggs that will hatch into a small squid larvae. The cephalopods are highly protective of their young ones. They cook care of them by cleaning, feeding and defending them from the attackers or threat of danger to the extent that female squid could die because they can’t defend it self because they are too weak.

Echinodermata

Echinoderms reproduce sexually, with male and female individuals releasing gametes into the water. The larvae that result are small and lightweight, like many other floating organisms. They transform into the relatively immobile adult form in order to grow and produce more gametes.

Answer 3

They have reproductive organs. There are various ways they do this depending on the organism.

Answer 4

Eww. Believe it or not, they do. :-/

I've seen a lot of snails "do it." It's done in the same way as turtles do it- the male gets on top of the female's shell and you see this... thing (lmaoo) go underneath her shell (to her vagina, obviously). Snails sexually reproduce.

Answer 5

yes they do there sexual organs are found inside their bodies not on the outside which makes figuring out gender hard.

Answer 6

mollusks have a "hypodermic" that they stab the other with to deliver the sperm. Echinoderma lay eggs, the male parts then spew sperm and fertilize them.

Answer 7

exchange bodily fluids by rubbing tenticles together...whats wrong with you...this is a well known fact!