Posts Tagged ‘megalopae’

Plankton light traps

November 5, 2015

Light traps2

At 5:45 pm on 2 November, 8 light traps designed to capture plankton were suspended off the Pearson College dock.

Light traps

Light trap

Marine Science students retrieved the traps the next day and examined the plankton that were captured.

Jazmin

We saw some very cool critters including many copepods with egg masses:

Copepod

And a polychaete worm and a crab megalopa larva:

Polychaete & megalopaMegalopa

More megalopae and nifty nereids

June 12, 2013

Nereis in distance

After a question from Johan about ‘weird, somewhat disgusting, sea snake/fish slithering around the surface’ at night and from Max (Dock worker extraordinaire!) about ‘long skinny creatures’ ranging in size from 6″ to 1′, I thought I better go investigate…

Max also sent the photo above and the two below:

Nereis Max1 Nereis Max2

These creatures are what I learned as Nereis brandti but are now called Alitta brandti.  Learn more about these giant pileworms from:

Alitta brandti at Encyclopedia of Life

Nereis (Neanthes) brandti at Invertebrates of the Salish Sea

Alitta brandti at World Polychaete Database

Megalopae2

On Sunday 2 June we hung a light off the Pearson College dock which attracted many, many megalopae (Dungeness crab, Metacarcinus magister).  Periodically a worm would also be attracted to the light.

Nereis & megalopae

I did pester a few of the worms and they released big clouds of sperm.  The reproductive strategy is called epitoky where the posterior end of the polychaete worm is transformed into a bag of gametes (either sperm or eggs). The epitokes swarm at the surface and then explode to release the gametes. Crazy but cool!

The megalopae are here!

May 31, 2013

While the students deserted us on 24 May, the Pearson College dock has thousands (maybe hundreds of thousands?) of visitors right now. The final larval stage of the Dungeness crab (Metacarcinus magister) is called a megalopa and there a many, many megalopae swarming around the dock.

Megalopa

Megalopae1 Megalopae2

On the dock, there are also thousands of juvenile crabs scrambling around.  The megalopae molt and metamorphose into the benthic juvenile stage seen below.

Juvenile

Megalopa & Juvenile

Megalopae & Juveniles

There are also many megalopae and juveniles on the succession substrates that students put in the water in September 2012.

P1010745 P1010746

P1010707 And Ivan thought nothing was using his wire!

P1010744