August Nature Sightings

Among the most talked about nature sightings this past week were two groups of animals at opposite ends of the marine ecosystem: sharks and salps. Shark sightings prompted lifeguards to close several ocean beaches on Long Island for swimming, while staff scanned the waters for signs of the shark’s classic dorsal fin.

It is a well known fact the sharks inhabit our ocean coastal zone, as they have for many years. It’s possible that the presence of bunker schools close to shore have enticed sharks, as well as dolphins and whales, to venture into the shallow waters where swimmers and bathers gather.

Long Island is within the range of several species of shark. One very nice photo of a shark in 2 to 3 feet of water, and identified as a black-tip reef shark, that was sent to me resembled our common smooth dogfish. While it is classified as a shark, its flat, sandpaper-like teeth are designed for crushing shellfish and it is quite harmless.

As a large top of the food chain carnivore, sharks, along with wolves and mountain lions, have had a long history of bad press (including the label “man-eaters”) and their respective populations have suffered tremendously at the hands of Homo sapiens. Much research by ecologists has documented the importance of these animals as large predators in their respective ecosystems, and the need to protect them is key to protecting the various components of a healthy ecosystem. Translating that concept to the general public is not easy, as the Long Island Coyote Study group is finding with our featured species: the Eastern coyote.

The salp is a representative of an unusual cluster of organisms called Tunicates (a tunicate that you may be familiar with is the sea squirt) in the phylum Chordata, which includes us. Most animals in Chordata are vertebrates, that is they have a skeletal framework of bone or cartilage. Tunicates lack vertebrae, but made the Chordata team, and are related to us, by the fact that they have a supporting rod and simple nervous system called a notochord, a very important part of our anatomy during our fetus stage.

The salps that showed up en mass in the ocean this past week resembled clear jelly beans in size and shape. One member of the Bonac Open Water Swim group reported that they were so numerous in the nearshore area of the ocean that it was difficult not to ingest a few during a long swim; the consensus was that they did not taste like jelly beans.

The surf washed many of these creatures up onto the beach where they formed a major component of the wrack line. The fresh deposits had many beachgoers wondering what they were looking at: fish eggs? Small jellyfish? A few hours in the sun dried the mass out to form a gray-colored, gelatinous sheet on the sand.

The last time I noticed large masses of salp on our ocean beaches was in 2018. At that time, I was not certain what they were and contacted one of Long Island’s most knowledgeable naturalists, Jim Ash, for an identification. A difficult person to “stump” with a natural history question, Jim did not disappoint.

Of course, I’d never heard of an organism called salp, so I had to refer to some reference books for an overview of their natural history and role in the marine ecosystem.

A salp is essentially a sac with two openings: one is the “mouth” that siphons in water and food; the other is the anus where fecal pellets and water are excreted. Circular muscle bands control the movement of water through the barrel-like organism. A mucous membrane inside the sac collects phytoplankton as water passes over it and conveys this food into the most visible portion of the creature: its digestive tract.

At first glance, they may appear to be very simple, relatively unimportant, marine organisms. That is deceiving. Their physiology, life history, and ecological niche are all fairly complex. Salps are among the fastest growing multicellular organisms on earth, enabling them to quickly exploit phytoplankton blooms.

They are generally warm water creatures found at the outer edges of the Gulf Stream, and periodically pushed shoreward by storms. Scientists report that swarms of salp are increasing worldwide as sea temperatures rise and could, in turn, change marine ecosystems from fish-dominated to tunicate-dominated systems. They also play an important role in the earth’s carbon cycle. Salp tissues are one third carbon by weight. Factoring in their abundance and short, explosive life cycle, salp corpses on the bottom of the ocean comprise a significant carbon sink that scientists are studying.