Hey, have you ever heard of a heteropod? You may have heard that term associated with terrestrial spiders, but what I am talking about is a group of very special marine snails! Hi, I’m Kris Clark, a graduate student from the University of South Florida College of Marine Science, studying marine gastropod molluscs collected from the DEEPEND cruises. My little creatures are within the Superfamily, Pterotracheoidea. These floating sea snails, commonly called heteropods or sea elephants (albeit they are generally small), are found throughout the world’s oceans in tropical and subtropical waters where they have adapted to pelagic (open sea) living. I like the name sea elephant as it describes their resemblance to an elephant’s trunk. These animals have an extended proboscis or nose-like feature that terminates with their mouth. The term heteropod was coined for these little beasts back in the 1800’s when they were first realized. The term was used because of the evolutionary development of their swimming fin from their ancestral foot – hetero meaning “different” or “other”.
There are three family groups that are categorized by the type (or lack) of a shell. Atlantidae have a full shell where the animal can fully retract inside. Carinariidae have only a very tiny partial shell that covers their visceral mass and gills. And lastly, the Pterotracheidae lack a shell entirely. All heteropods have mostly transparent bodies, have an evolved foot that now serves as a swimming fin, have a mobile proboscis for feeding, and have spherically gelatinous eyes for locating prey. They feed on copepods, polychaetes, brine shrimp, salps, tiny crustacea, jellyfish, pteropods, and other heteropods.
Most people have not ever heard of heteropods. And that’s not surprising. This group of sea-life is still understudied, however more investigations are developing, including mine. One important and interesting finding about heteropods is that there are a lot of them in the oceans. And since they are found in every ocean and are very abundant it is estimated that these swimming snails are highly important to the ocean foodweb – mainly fishes rely on the heteropods to eat, and larger prey eat these fishes, and so on. So heteropods post an important position in the food hierarchy in the ocean system. Many other compelling attributes have been discovered about little heteropods… keep in touch with our future articles for more curious discoveries!
Want to learn more now? Check out these fun videos of swimming Pterotracheoidea…
After a 2 day weather delay, we are back on track today. As usual we began sampling at sunrise.
We caught bucket loads of jellyfish.
And a really cool moonfish!
After competing all of our sampling stations, we are ready to pack up and head to shore. Thanks for following along with us!
Today started out with rain and lightening delays but quickly turned to rainbows.
Last night's dip netting resulted in more myctophid samples. These will be used for the otolith chemistry component of our project.
This billfish from today's sample was exceptional!
We finished up the sampling at sunset with a total of 12 stations.
We had a great second day out on the water. Last night we caught some neat myctophids in the ring net.
Mike, Kim and Chris also had good luck with the dip nets at night! Here is one of the flyingfish they caught.
Today we completed stations 15-24 which finished our first transect. We caught tuna, billfish, flying fish, and a dolphinfish. This is one of the larval tunas.
Now we are traveling to the beginning of our second transect, which is about a 7 hour steam. We will be ready to start sampling at dawn tomorrow!
We have just complete our first day of sampling on the LF2016B Cruise aboard the Blazing Seven. Our crew consists of 9 researchers including: Dr. David Wells, Dr. John Mohan, Cori Meinert, Mike Lewis, Chris Steffen, Jessica Lee, and Jillian Gilmartin from Texas A&M University at Galveston and Sebastian Velez from Florida Atlantic University. We sampled at 14 stations today and had some interesting finds including billfish, swordfish, and a puffer.
We will be towing the ring net again tonight, so look forward to pictures from the deep!