13 December 2011 So How do you Tell a Male Copepod from a Female Copepod?

We had BIG excitement yesterday...we saw the SUN!!! Even though we have been South of the Arctic Circle, the sky has been completely cloud covered every day. Stormy weather, overcast and gray skies made it difficult to see where the water met the sky. That was NOT the case yesterday...we were so happy for the return of the sun!!

We also had a special fly by yesterday. A Coast Guard C-130 aircraft doing ice reconnaissance in the area did a double fly by past the Healy. It was incredible seeing blue skies, sunshine, beautiful clouds AND the C-130!

Working with the scientists aboard Healy for the last 39 days, I have learned many things. In the beginning, I had difficulty recognizing the difference between male and female copepods. Celia would say, “after looking at enough copepods, your eyes will just SEE the difference”. Yesterday my eyes FINALLY saw the difference. I successfully picked and sorted copepods – males, females and C5 juveniles.

Male copepods have 5 urosome segments. The urosome segments are like the “tail” segments – even though you are not supposed to call it a tail. Their antennae are also very thick at the base where they connect to the head.

Female copepods have 4 urosome segments. They have a genital pore on the first urosome segment closest to the body. This pore is slightly swollen and looks like a bubble. Depending upon the way the copepod is positioned under the scope, you may actually see both sides of the genital pore. This female copepod has a fecal pellet in her digestive tract.

In order to reproduce, male copepods grasp the female copepods' antennule and attach a spermatophore from his genital opening to the genital opening of the female copepod. Female copepods can store sperm for a long period of time.

C5 juveniles have 4 urosome segments like the female copepods, but they are lacking a genital pore.

Can you imagine having a sample with many different types of zooplankton and having to differentiate males, females and C5's? It was a challenge, but I am so glad I finally was able to complete the task!

We were treated to a gorgeous moon and frazil ice as we transited to Nunivak Island.

New Vocabulary

Urosome - The abdomen, or post-abdomen, of arthropods.

spermatophore - A capsule or compact mass of spermatozoa extruded by the males of certain invertebrates and primitive vertebrates and directly transferred to the reproductive parts of the female.

antennule - A small antenna or similar organ, especially one of the first pair of small antennae on the head of a crustacean.

 Stay tuned as we continue our exciting voyage on the USCG Cutter Healy. Until then...

“Live as if you were to die tomorrow. Learn as if you were to live forever.” Mohandas Gandhi