Seamounts Species Spotlight: The Jelly-Like Ctenophore

The New England Coral Canyons and Seamounts are a special area 150 miles off the coast of Cape Cod. The unique geological formations make this area a biological hotspot, attracting many unique species. This blog post in part 4 in a series that profiles some of these incredible animals.

Glowing water is not just the stuff of sailor stories and fairy tales. In tropical regions, when the briny depths appear to be glowing, it is most likely a result of bioluminescent plankton. But here in the North Atlantic, there may be another culprit: the ctenophore.

Also known as “comb jellies” and “sea walnuts,” the ctenophore is a nearly transparent floating creature frequently misidentified as jellyfish. While similar, the ctenophore is actually in a phylum of its own (lower than kingdom; higher than class). This is due to differences in ctenophores and jellyfish in how embryos develop, and the physical appearance of adult individuals. Scientists estimate there are 150 species of these jelly-like creatures, found throughout the water column and in all the world’s oceans.

Important Differentiators 

Don’t worry if you see a ctenophore in the water – unlike jellyfish, ctenophores aren’t able to sting humans. To hunt for food, some do deploy tiny stinging cells, while others can engulf prey even larger than they are!

While there is no “typical” way to describe the ctenophore’s physical features, scientists can agree on a few facts: First, ctenophores are invertebrates, meaning they have no bone structure. This makes them appear to be simply floating in the water. Almost all species are small and transparent. One exception to this rule is the beautiful and large “Venus’ Girdle.” This species can grow up to a meter in length, is pale violet in color, and is found in the Mediterranean Sea. Almost all ctenophores are bioluminescent, meaning they glow.

A ctenophore can appear to be rainbow colored because when it swims, tiny hair-like structures on the outside of its body beat together so quickly that it deflects light into tiny rainbows. These fast-beating hairs are called cilia. Cilia are found arranged in eight rows on the outside of all ctenophores.

Although the ctenophore can live in many places throughout the water column and in most habitats, benthic (seafloor) varieties are difficult to come by. This makes them very challenging creatures to study, leaving scientists with much to learn about them.

In 2013, NOAA conducted an Okeanos Explorer Program Expedition within the New England Canyons area and had the rare opportunity to view and record a number of ctenophores (and many other unique critters). Clearly, an abundance of research opportunities lay in the lively communities of the Coral Canyons and Seamounts.

This is another reason why permanently protecting unique ocean habitats is so important. Who knows – this research that may provide marine science with its next big discovery!

Leatherback Turtles Really Get Around

Did you know that one of the largest living reptiles on the planet can be found in New England’s ocean? Leatherback turtles, like the one shown above, can weigh up to 2,000 pounds and grow to 11 feet long. They are true ocean cruisers – you can tell by their giant flippers that they are built to cover great distances. They are at home from the tropics to Newfoundland and have been observed traveling almost 13 thousand miles in under two years. One of the reasons they wander is in search of their favorite food – sea jellies, and we have a lot of those in New England in the late summer and early fall.

As a vivid reminder that these sea-faring turtles enjoy our Gulf of Maine waters, last September an enormous leatherback was found, stranded, near the tip of Cape Cod. Normally, there is a well-oiled turtle rescue and rehabilitation machine in New EnglandMass Audubon Society volunteers transport the turtles to New England Aquarium facilities for treatment and release back into the wild – but they are used to dealing with much smaller turtles, usually well under 100 pounds. 

But the stranded leatherback turtle on the Cape was much larger – it was ill and underweight yet still weighed in at 655 pounds – and posed some unique challenges to rescuers and rehabilitators.  Using equipment normally reserved for dolphin rescues, volunteers managed to transport the leatherback to the care of the New England Aquarium. But that was just the beginning of the struggles to help the turtle. According to New England Aquarium’s Tony LaCasse, these turtles are open ocean animals that are not hardwired to recognize barriers, so they can crash into walls and hurt themselves. In addition to needing staff on hand to prevent turtle/wall collisions, this leatherback was so weak it needed help surfacing to breathe. Fortunately, the Aquarium was able to provide all the turtle needed to begin its recovery. You can read more about how the Aquarium handled this huge animal with extraordinary effort and care on their rescue blog.

After two staff and labor intensive days of caring for the leatherback, the experts at the Aquarium decided that releasing him back to the wild would give him the best chance of survival. They fitted the turtle with a satellite tag to learn more about his recovery and behavior, then released him on the “Sound side” of the Cape, where he would not be at risk of getting trapped in Cape Cod Bay.

Once released, the leatherback headed straight for the east end of Nantucket, a spot known for having a high concentration of sea jellies. After that, he quickly headed south to the relatively warmer waters of coastal New Jersey, and eventually moved on to Bermuda. The last time Aquarium scientists checked on the turtle, he was still alive and on the move.

It is a heartening story, and a good reminder of the amazing things that lie beneath New England’s waves.

Technicolor Sea Slug Floats Like a Butterfly and Stings like an Anemone

 

From its ghostly see-through body to its flaming punk rock spikes (called “cerata”), this nudibranch (Flabellina nobilis) combines style with substance – and a nasty substance at that.  Nudibranchs are mollusks, but they have no need for a shell (in fact their name means “naked gills”). This animal, which Brian Skerry spotted in shallow waters off the coast of Rockport, MA on a recent dive, may look squishy and helpless, but its tender pale body and sweeping orange fronds belie a deadly arsenal cached in its cerata. The Flabellina nobilis has an amazing talent: it can hijack biological weapons from its prey and store them away for later use.

The nudibranch in this beautiful picture is eating hydroids — small relatives of jellyfish and anemones (the little red feather dusters you see scattered around the photograph). Hydroids have “nematocysts,” or tiny coiled up harpoons that shoot out when the animal is disturbed and inject the intruder with an irritating — or even deadly — toxin. The nudibranch collects these nematocysts as it eats and moves them up to the tip of its cerata, for later deployment as necessary. Not many things will try more than once to eat a nudibranch that is this well defended. As if all that wasn’t cool enough, the nudibranch uses pigments in the hydroid to dye its snazzy ‘do. A fine example of the old adage: you are what you eat.

Some nudibranchs can also concentrate toxins from food they eat and store it in their tissues, making them very unappetizing and possibly poisonous. This nudibranch is not known to reuse toxins from its food, but scientists think that it may be able to produce its very own brand of poison in-house. Either way, it’s not a good snack food.

Nudibranchs are found in all the world’s oceans, but this species likes the cooler waters of New England and the North Atlantic. So now that you know a little more about this beautiful animal, you can look for them yourself. But remember: look, don’t touch!