Monday, July 27, 2009

Chondrichthyes conundrum

Hello again! This is Janet coming to you live from the Save the Harbor main offices on the Boston Fish Pier. This morning we had our weekly program staff meetings, where we gather all 17 of our summer program staff members and some Dunkin Donuts "Munchkins" in one spot to talk about last week's explorations and next week's adventures. As we went around the table we found ourselves discussing once again the skate that was caught a few weeks back at Camp Harbor View. Skates are of particular interest to me because they belong to my favorite class of fish (and also a great hangman word), Chondrichthyes!

As you might know scientists divide all known living things into groups based on certain characteristics (this is called classification). You could try the same thing with a group of friends by choosing a characteristic - for example the type of shoes people are wearing - and then divide them into groups based on that characteristic, such as those with flip flops, those with sneakers, and those with everything else!

The basic idea behind classification is that creatures who belong to the same group share common characteristics and are related to each other. So fish in the class Chondrichthyes are similar because they all are jawed fish with cartilage skeletons (plus some other specifics related to their physiology but we won't get into that here). Cartilage is the same material found in human ears and noses - a very flexible but strong connective tissue. In fish from the class Chonrichthyes, such as skates, rays, and sharks, cartilage makes up the entire skeleton - so there are no bones!!

Because these creatures live in the water they can still grow to pretty huge lengths (whale sharks - which are the largest fish in the ocean, grow up to 45 feet long) even though they don't have bones. If they were on land, the creatures would need to be much much smaller, as they would not be able to support very much body weight with just a cartilage skeleton!

More fun facts soon!!!

Best fishes,


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