To recap, I’m trying to see if the marine life featured in The Little Mermaid is congruent with a fan hypothesis that Eric’s Kingdom was in Denmark and Triton’s capital city was in the North Sea. In Part 1 I looked at the distribution of coral reefs around the world. But the poorly studied deep-sea corals, including the geographic location of deep-sea coral reefs, meant that little could be inferred. Today, I’ll focus on numerous other species highlighted in the movie.
The crux of this post is based on species distributions. Species distributions are an essential part of ecology. Although humans can live everywhere (well anywhere as long as we have our snazzy technology like fur pelts during the Ice Age or air conditioning today), many species are restricted to living in a narrow geographic range. Biologists often want to understand what environmental factors contribute to where species live. For example- the giant panda only eats bamboo, thus its range is restricted to bamboo forests. But there can be many environmental variables that contribute to a species distribution, and biologists use statistics and machine learning to build ecological niche models which can infer which variables are the most important in determining a species’ range. These models are particularly useful for conservation, allowing us:
- to predict where invasive species will find suitable habitat,
- to identify where to reintroduce species to establish new populations to extend their range, or
- to predict where species will live in the future as the climate changes.
While I won’t build any species distribution models today (although I will if someone posts a link to worldwide oceanic variable datasets in the comments), I’ll use presence data to see if species in The Little Mermaid occur in the North Sea.
After we meet Ariel and Flounder, they are chased by a Great White Shark (Carcharodon carcharias). Great White Sharks are vulnerable to extinction due both to entanglement in fishing gear or direct killing as they are a perceived threat to humans. Direct killings also occur to provide shark fins to wildmeat markets, and fins, teeth, and jaws to luxury goods trade. As a near-shore species, shark habitat has degraded due to pollution and development. Additionally, overfishing reduces their food supply.
Great White Sharks are a marine species that live in temperate waters; however, they occasionally occur in tropical or boreal waters. From the presence localities in the picture, we can see that they live on continental shelfs, although migration through open water has also been recorded. More important to our Little Mermaid question, the presence locations do not suggest that Great Whites occur in the North Sea, although over 30 other species call these waters home.
Les Poissons (hee-hee-hee haw-haw-haw)
Sebastian’s famous song, “Under the Sea” is rather morbid when you listen to the lyrics (watch it here on YouTube). It’s meant to scare Ariel not to go to the surface because fish become food for land-lubbers. Sebastian’s lyrics focus on explaining how happy fish are when they remain “under the sea;” and he gives us a huge list of economically important species including:
- Carp (several species within the family Cyprinidae)
- Plaice (Pleuronectes platessa)
- Bass (several species within the order Perciformes)
- Chub (several species within the family Cyprinidae)
- Ray (several species within the superorder Batoidea)
- Ling (Molva molva)
- Trout (several species within the family Salmoniae)
- Blackfish (Tautoga onitis)
- Smelt (several species within the genus Hypomesus)
- Blowfish (several species within the family Tetraodontidae)
The first thing that is notable about all of these species is that some are marine (blackfish, blowfish, smelt, plaice, ling, bass) and others freshwater (chub, carp, trout, bass). Thus, even if we could identify the specific species from the common names given, they would not all occur together. Whether a fish is marine or freshwater is a big deal, and would certainly be an important variable for a species distribution model. Salinity affects osmotic pressure within a fish’s body. The kidneys of marine species must excrete salt, where the kidneys of freshwater fish must excrete water. This is how fish maintain the correct osmotic balance, and without osmotic balance the cells of the fish would fill with water until they burst, or completely shrivel.
The three species that we have scientific names for (blackfish, ling, and plaice) are all marine, so now let’s see their species distributions. While blackfish are endemic to North America, ling and plaice have high occurrence patterns in the North Sea, and have also been sighted in the Norwegian, Baltic, and Mediterranean Seas.
Such a Sweet and Succulent Little Crab
There’s a lot of online debate if Sebastian is a lobster or a crab (no small question, they diverged ~375 million years ago). Disney has actually put this to rest and stated that he is a red Jamaican crab. Here’s the problem, there are no species with the common name Red Jamaican crab (hence scientists’ hatred of non-Latin names). But I did find a Red Land Crab (Gecarcinus ruricola) that is endemic to the Caribbean Sea and Gulf of Mexico. However, this species lives on land versus the sea.
So how does this information about Sebastian’s species distribution fit into our overall picture? When all the evidence is considered together, the distribution of corals, Great White Sharks, economically important fish, and an expat crab, we must conclude that Disney totally made up the ecosystem which Ariel calls home. While disappointing that no strong conclusions can be drawn to infer the locale of The Little Mermaid, take heart that scientists use species distribution models to much greater effect. But as these posts have highlighted, there is a lot of missing data. Too often I catch myself thinking there are no questions left to answer, but we don’t even know basic stuff like identifying all the species (come on, there MUST be a black and purple octopus like Ursula waiting to be discovered) or mapping species’ full ranges. Filling the gaps in what we know is such a fun part of being a scientist, and sometimes it takes a silly exercise like this to find those gaps.
Until The Little Mermaid II- Return to the Sea. And yes, I own the VHS of that too.