Spider rock crab

Day 7

Today was full of new experiences for the whole PSJ crew. We took the first steps to explore the aquatic invertebrate animals present in the Punta San Juan ecosystem. Dr. Matt Allender joined our trip this year to spearhead a project looking at the health of invertebrates as a tool to monitor the health of the PSJ ecosystem. Invertebrates, such as crabs, starfish and urchins can be good indicators of water quality and environmental contamination because they spend their lives in the ocean water.

Today we performed physical exams and took blood samples on spider rock crabs and sea urchins. Many people are surprise to learn that you can even do an exam on an invertebrate, let alone collect samples. Despite the cooler winter temperatures (which are still in the 50’s and 60’s) right now, we donned wet suits and braved the 50 degree water to try to find crabs this morning. The crabs rest on rocks in the surf, just out of the water. The surf can be very strong and rocks are sharp, but the biggest surprise was how quickly the crabs could move! They were surprisingly difficult to catch and also spit water at you (in addition to pinching). With a little help from the Peruvian crew, we were able to catch and examine about 20. They all appeared to be in good health. We took measurements and weights, performed exams, collected samples, and finally returned them safely to their tide pools.

By crawling around on the rocks in the surf, we attracted the attention of two curious fur seals who would come by periodically to watch us work. Mike and I were also able to spend a few minutes watching some of the wildlife from the near shores water. Surprisingly, most of the fur seals and penguins ignored us when we were in the water and came very close to us. It was breathtaking to watch these animals up close. It was also rather breath-taking in a different when the occasional wave would crash over our heads. It’s amazing to see how effortlessly the seals and penguins can swim through the waves and how unfazed they are by the frigid water.

This afternoon we moved to a different beach to search tide pools for sea urchins. They were much easier to catch (they are essentially sedentary). We performed exams and took blood samples from about 15 urchins. Sea urchins not only have strong, partially calcified spines but also have tube feet which together with the spines help them move around the ocean floor and wedge themselves into rocky crevices. The circulatory system of sea urchins is “open” meaning instead of vessels directly supplying each organ, the vessels ferry blood to an area of the body and nutrients are supplied by “bathing” the organs. The circulatory system also communicates with the external environment. For most invertebrates, we still do not have established normal values for blood (called hemolymph), so in taking samples from healthy animals we will establish normal values for this population. They are dynamic animals and were fun to work with. Since invertebrates are sensitive to environmental changes, changes in their health and populations may be a good indicator of health in the PSJ ecosystem. We hope to continue building this project and expanding our research efforts in new directions. The pilot study this year provided us with great data to plan additional invertebrate projects.


Gwen Jankowski, DVM
Veterinary Resident – Brookfield Zoo

June 13, 2010

Dr. Allender collects a blood sample from a crab

Dr. Adkesson examines a crab

Collecting a blood sample from an urchin

Dr. Jankowski and the team examine and collect samples from an urchin

Collecting samples from invertebrates

A curious fur seal pup

The surf at PSJ

Day 1-June 7, 2010
Day 2-June 8, 2010
Day 3-June 9, 2010
Day 4-June 10 , 2010
Day 5-June 11 , 2010
Day 6-June 12, 2010
Day 7-June 13, 2010
Day 8-June 14, 2010