Sunday, July 19, 2009

Love is in the Water

It seems as though true love is blossoming before our eyes as the opposing genders of many species become better acquainted. Events such as: spawning sea stars and sea cucumbers, eggs from Oregon Hairy Tritons and various nudibranchs, and the claws-on mating of the Red Rock Crab are spontaneously occurring at the Ucluelet Aquarium. It is a good idea to breed when the warming water supports more growth as the success rate of young increases.

The predatory Hairy Oregon Triton has begun laying eggs in a beautiful spiral shape on the window of one of our tanks. This animal is suspected to have the longest larval development period of any marine invertebrate- up to four years. They will wait to undergo metamorphosis until there is adequate food to support their growth. The appearance of the eggs indicate that 6 - 9 months earlier a snail couple had intimate relations in which internal fertilization occurred. The snail will now protect these eggs for up to nine weeks from predators before the young larvae hatch. These hairy guys are covered in periostracum which are brownish bristles aiding in camouflage, when fully grown the snail will span up to 6 inches across.

Hairy Oregon Triton laying their eggs in a spiral pattern on the glass tank. [Mary Vasey]

When it comes to crab it's all about tough love as demonstrated by our Red Rocks. The male- generally much larger than his partner- will hold the female and wait for her to moult. This period can often take several days. If the female does not moult and the males appetite gets the best of him then he will eat her! Assuming that she doesn't become a snack mating will take place usually within a few hours. Both the female and male will open their abdomens and reveal their spermathecae and gonopods, respectively. Using his gonopods the male release packages of sperm into the female that she can hold for several months before fertilizing her waiting eggs. Need a visual? Okay!

Red Rock Crab action. [Mary Vasey]

Strangely, nudibranchs are simultaneous hermaphrodites meaning they are capable of holding both egg and sperm at the same time. The advantage to this is that when two nudibranchs of the same species cross paths they are definitely able to mate unlike if they were both males or both females. Both nudibranchs will fertilize their partners eggs and also receive sperm. The egg spirals are then laid in lacey-looking coils. These coils differ depending on the species and will be eaten readily by other species. Because nudibranchs live only a year so copulation is constant throughout the year.

So there you have it: the delicate art of marine animal courtship can be seen by you, here, at the Ucluelet (mini) Aquarium.

The shells of the veliger stage of these moonsnails are visible between the grains of sand that protect these young. [Aquarium Staff]
Sea stars release egg and sperm during broadcast spawning. These gametes are viewed under the microscope. [Aquarium staff]

-Mary Vasey, Interpreter

1 comment:

Anonymous said...

I have just had a look at your website. Great pictures and interesting work in educating the public. It looks like you guys are doing a great job.
Sparked my interest enough that I want to visit.