Bro, snails?….Really

First of all , no. not JUST snails. Would you like them more if I told you they are also known as “sea butterflies”? See, Pteropods are a type of planktonic gastropod (a type of snail, yes) that live in the ocean. They’re called “sea butterflies” because of the way they move through the water, flapping wing-like appendages known as parapodia. These wings help them glide through the water, much like butterflies flutter through the air.

They come in two main types: Thecosomes, which have delicate, transparent shells (my favorite kind), and Gymnosomes, which are shell-less and predatory (It’s ok if you hate these ones). These tiny dudes can be found throughout the world’s oceans, from the warm waters of the tropics to the icy polar regions. Most live in the upper layers of the ocean, typically in the top 300 meters, where they are an important part of the plankton community, forming the base of the food web.

Some species of pteropods also undergo vertical migration—they move up and down the water column daily. During the day, they descend to deeper waters to avoid predators and come back up to the surface at night to feed. This migration helps them stay safe while still getting access to food. Most feed on phytoplankton, microscopic plants that float in the water. They use special mucus webs to trap their tiny prey(very cool, very Spiderman coded).However, some pteropods, like gymnosomes (I hate these guys so much man), are more predatory and prey on other small animals, including other types of pteropods!

Pteropods reproduce by releasing eggs and sperm into the water, where fertilization occurs externally. Once fertilized, the eggs develop into larvae, which eventually grow into adult pteropods. Interestingly, some species are hermaphroditic, meaning they have both male and female reproductive organs. This can make it easier for them to reproduce, as they don’t need to find a specific mate of the opposite sex.

Even though they’re small, pteropods are a crucial food source for many larger marine animals. Fish such as salmon and mackerel depend on pteropods for food, especially in polar regions where pteropods can make up a significant portion of their diet. Some species of whales like the Bowhead, Minke and Humpback (My 2nd favorite whale type. You’d think it’d be a conflict of interest for me here but I like Humpbacks a whole lot more than I like pteropods so it’s ok if they get eaten by them) also rely on pteropods, consuming them in large quantities. Seabirds like the Northern Fulmar and Black-legged Kittiwake (actual birds fr) are also  known to eat pteropods, diving into the water to scoop them up. Because they’re such a critical food source, pteropods are an important part of the marine food web, especially in cold-water ecosystems like the Arctic where those birds live.

Why I love these guys

OK, now this is the cool part. See, these guys are an essential part of the marine food chain, acting as a primary food source for many larger animals. Without them, many species (like the whales and birds mentioned) would struggle to find food, which could disrupt the entire ecosystem. At the same time, they also play a part in the carbon cycle. When pteropods die, their calcium carbonate shells sink to the ocean floor. This helps transport carbon from the surface to the deep ocean, where it can be stored for long periods, effectively removing it from the atmosphere and helping to regulate global climate.

With me so far? good. Now, one of the biggest threats facing the planet today is ocean acidification. As the ocean absorbs more carbon dioxide (CO₂) from the atmosphere, the water becomes more acidic. When the ocean becomes too acidic, pteropods struggle to maintain their shells, which can become thin and weak or even dissolve completely. This makes them more vulnerable to predators and less likely to survive. Ocean acidification is particularly problematic in colder waters, where more CO₂ is absorbed, meaning that pteropods in polar regions are especially at risk. 

So, Because of their sensitivity to changes in ocean chemistry and their role at the base of marine food webs, pteropods can be used by scientists as bioindicators—organisms that provide scientists with clues about the health of the ocean. By studying how pteropods are affected by acidification, scientists can gain insights into the broader impacts of climate change on marine ecosystems. isn’t that cool? Basically, if you can collect a group of pteropods and check how full their shells are, you can tell with a degree of certainty how healthy or unhealthy that part of the ocean is. They are basically a cheat sheet for marine scientists! As a chemistry major, I want to research these guys so bad especially in the context of climate change.

As we continue to study pteropods, we learn more about the challenges facing our oceans and the steps we can take to protect these vital ecosystems. By understanding the delicate balance that pteropods help maintain, we can work toward ensuring a healthier future for the planet. Now enjoy this gallery of pteropods on me