Week Two: Invertebrates Continued

Sylvia Yamada

Monday April 4th-  

The week began with two guest speakers Sylvia Yamada and John Chapman. Sylvia took us out to check crab traps that had been set out the day before. We identified the species of crab we caught and tallied how many of each we found.  In the deeper traps we found Cancer productus (Red Rock Crab) and Cancer magister (Dungeness Crab) and in the shallower traps we found two species of shore crab; Hemigrapsus oregonensis (Green Shore Crab) and Hemigrapsus nudus (Purple Shore Crab). One way to differentiate between these two species of shore crab is to remember that Hemigrapsus oregonensis is hairy and like Sylvia reminded us, “Oregon girls don’t shave their legs!” 

Sylvia’s lecture focused on the introduction of the invasive European Green Crab, Carcinus maenus, which we learned was introduced to the San Francisco Bay in 1989, or at least that's when it was discovered.  It was later brought Northward by the El Nino event in 1997-1998, which resulted in unsually warm water temperatures, unusally strong poleward currents, and downwelling, all of which contributed to creating the extremely large year class of 1998.  We learned that the strength of the each year’s recruits dependes heavily on ocean conditions, because as larvae, Carcinus maenus is pelagic and at the mercy of the ocean’s currents and temperature.  




John Chapman

 Our second guest speaker was John Chapman, an expert and researcher on a parasite of the of Upogebia pugettensis (Blue Mud Shrimp).  Orthione griffenis is a parasitic isopod newly introduced to the Pacific North West that attaches to the gills of Upogebia pugettensis and feeds on its blood.   Upogebia pugettensis is capable of living with this parasite, but it has been found that mud shrimp with the parasite were an average of 7.8% lower weight than similar sized individuals without the parasite.  After prolonged parasitism, Upogebia pugettensis is unable to reproduce as most of its energy and nutrients are being diverted

 to the lump on the side of its carapace.

                                                                                     Tuesday, April 5th-

The following day we had the opportunity to go find our own mud shrimp at Sally’s Bench in the mudflats at Yaquina Bay. Nothing like a morning spent sinking, swimming, sloshing, and trudging through the mud! It was quite the sight to see everyone crawling on thier hands and knees through the stuff and we had a lot of fun. We found two species of mud shrimp, including the Upogebia pugettensis (Blue Mud Shrimp) and Neotrypaea californiensis (Bay Ghost Shrimp). We found the parasitic isopod, in addition to a small clam attached to Upogebia pugettensis.  We also collected an interesting scale worm and other creepy crawly critters.

Wednesday, April 6th-

In addition to our last three lectures on Wednesday, Tom, the sea water system maintenance guy, was nice enough to give us a tour of the sea water system that keeps Hatfield up and running.  Maintaining the sea water system is a constant job and is more difficult than one might think. For example, marine fouling is a huge problem in the pipes, so every so often they send a “pig” through, which is a large object that shoots through the pipes, taking any marine organisms with it, and out the other side. It can shoot out of the pipes with a lot of force, and has been known to achieve long hang-times before finally landing on the beach. Remember, if you’re walking on the estuary trail, always be alert.

That evening was the 6th Annual Marine Invertebrate Presentation and Dessert Extravaganza! We all gave presentations on our favorite invertebrates in creative ways. There were a lot of laughs, and some of the highlights included: Pin-the-Parts-on-the-Nudibranch, a talk show featuring a crab with a (strangely) southern accent, a horseshoe crab piñata, an octopus rap, a sea nettle sales pitch, and an edible, chocolatey sea cucumber. There was even a guest appearance from David Attenborough! All around, it was a night of great educational entertainment.

Thursday, April 7th-
Thursday was devoted to preparing for our final exam.  We started it off with extremely helpful review sessions for our invertebrate final and lab practical (thank you Sally and Allie!). The rest of the day was ours to study, and study we did!

Friday, April 8th-
It was time to put our knowledge to the test and determine how much information we had absorbed over the last two weeks.  After finishing our final and lab practical, we cleaned out the lab and decided which invertebrate pets to keep.  Most people took off to Corvallis and beyond for a rare weekend free of homework!