Posted by admin | 02.03.2011 | Marine Science
Diving into Creatures of the Deep
A lone Humboldt squid made an extraordinarily long migration earlier this week. Known to travel up and down the Eastern Pacific seaboard, this squid was unique in that it didn’t swim to North Carolina – it drove. The Ashley High School Oceanography class received a donated squid from the Squids-4-Kids program part of the Monterey Bay National Sanctuary and the Gilly Lab.
The squid arrived frozen and was slowly thawed to make dissection possible. Sea Turtle Camp staff worked alongside UNCW researchers and NC Aquarium educators to provide instruction as students delved into the external and internal anatomy of their specimen.
Humboldt squid (Dosidicus gigas), also known as Jumbo Flying Squid, derive their name from the Humboldt Current, where they typically reside. They can reach up to 6 feet and 100 pounds in weight, but typically only live to be about a year old. The male squid that the Ashley students dissected was not quite full-sized, but it was certainly a well preserved specimen.
The dissection began with external anatomy. We first examined the differences between the arms and tentacles, noting the teeth-lined suction cups. Students were particularly impressed with the size of the eyes, making squid well suited to live at depth. We also had the opportunity to rub and contract the chromatophores (pigment cells) along the body, which allow the squid to change color.
Then the real fun began as we picked up our scalpels and made an incision up the mantle cavity. We removed the beak, lens from the eyes, stomach, liver, pancreas, esophagus, hearts (they have 3), gills, and reproductive organs. Students particularly enjoyed bursting the ink sac, writing their name along pieces of paper. When most of the internal anatomy was removed, students stared curiously at a long, thin clear plastic-like structure – the gladius. Like other mollusks, squid have a shell, but their shell is on the inside. The gladius is the remnant of the shell possessed by their ancestors and helps the squid control buoyancy.
Dissections of Humboldt squids are becoming more common in schools, since the squids are becoming more abundant. Scientists have noted that the range of the squids has increased dramatically over the decades, though there is debate as to whether this is climate related or due to lack of predators. Regardless of the cause, many Ashley students were glad that the squid could make a visit to their classroom, for a real hands-on, slightly smelly activity.