Buzz
Sirenians are a fascinating group of mammals that includes dugongs, manatees, and the extinct Steller’s sea cow. These creatures are known for their slow-moving, herbivorous, aquatic nature, often seeming to do little beyond feeding. However, that perception is misleading. They are truly remarkable beings that are critically endangered due to human negligence and require our urgent protection.
10. Their Name is Inspired by Mermaids
The term “Sirenia” is derived from the Greek word for “mermaids.” These creatures were named after mermaids because sailors once mistook them for such beings, not because they share any physical resemblance to the mythological half-woman, half-fish figures. It may sound like a fanciful tale or a mocking nickname, but there are actual historical accounts where this confusion genuinely occurred.
For instance, Christopher Columbus recorded in his log on January 9, 1493, that he had seen mermaids, describing them as “not half as beautiful as they are painted.” Perhaps the lengthy sea journeys and the constant absence of women led Columbus and other sailors to believe they were encountering mythical mermaids rather than a 700-kilogram (1,500 lb) sea herbivore.
9. Unusual Breasts and Other Curiosities
In nature, round breasts are a rarity. Only three groups of mammals have them: elephants, sirenians, and humans. This feature might have contributed to the confusion among sailors, who mistook sirenians for mermaids. The name “manatee” itself comes from the Caribbean word manati, which translates to “breast.”
Manatees and dugongs also possess other peculiar traits, such as having only six neck vertebrae. Every other mammal has seven, with the exception of sloths, which have eight or nine. Additionally, manatees and dugongs continuously regenerate their teeth throughout their lives.
Interestingly, manatees are the only known species in the animal kingdom to have a vascularized cornea, a feature typically linked to injury or infection. Despite its unusual nature, it seems to be a normal characteristic for manatees and dugongs, though zoologists are still investigating the reasons behind it.
8. They Don’t Resemble Their Close Relatives
When it comes to physical traits, sirenians resemble seals and walruses the most, with their flippers, stout bodies, and aquatic way of life. However, unlike sirenians, which are herbivores, seals and walruses are carnivorous pinnipeds.
In fact, the closest relatives to sirenians are elephants and hyraxes, despite their evolutionary split happening around 60 million years ago when the impact crater of the meteor that wiped out the dinosaurs was still warm. The connection between dugongs, manatees, elephants, and hyraxes is evident in shared features, such as spherical hearts, three or four toenails, similar skin and hair, and teeth that can be shed. Some species of sirenians even possess tusks.
Moreover, like elephants, sirenians are strict herbivores and use their upper lips to grasp food. Elephants have trunks, whereas sirenians have snout-like suckers. While manatees didn’t evolve from elephants, the evolution of sirenians itself presents a much more intriguing story.
7. The Evolution of Sirenians
At present, there are only four known species of sirenians: one species of dugong and three species of manatee. Some may mistakenly count five species, as the Steller’s sea cow, which became extinct as recently as 1768, is often included alongside the surviving species.
Throughout their history, over 60 species of sirenians have existed. Their evolutionary path has been thoroughly documented, unfolding in a tale as captivating as that of cetaceans. Sirenians, elephants, and hyraxes share a common ancestor that originated from a group of early hoofed animals known as condylarths.
Around 56 million years ago, sirenians began to spread across the waters of the world. Back in those times, their ancestors resembled hippos. These creatures were capable of walking on land and were roughly the size of a pig.
By about 33 million years ago, sirenians had adapted fully for an aquatic life. Their evolutionary journey is rich with transitional fossils that demonstrate their gradual shift from land-dwelling beings to fully aquatic animals. Over millions of years, sirenians didn’t confine themselves to one area but instead ventured across the globe.
6. The Global Expansion of Sirenians
For over a century, paleontologists have debated the origin of the sirenians: did they first emerge in the Old World or the New World? Fossils of early sirenians have been discovered in both Jamaica and Africa, leading scientists to seek an even earlier fossil to determine the true birthplace of this remarkable mammal group.
In the 1990s, the discovery of the Chambi sea cow fossil in North Africa provided key insights that helped solve the mystery. From this earliest known sirenian fossil, it became clear that the Chambi sea cow was a four-legged, semi-aquatic animal about the size of a pig. By piecing together fossils, geographic regions, and the layout of landmasses around 50 million years ago, experts have determined that sirenians once inhabited nearly all shorelines in both the Old and New Worlds.
Beginning in Africa, sirenians made their way to Europe, spreading throughout the Mediterranean and even reaching as far north as modern-day Germany. They also crossed the Atlantic Ocean through its northern end, where a land bridge once connected the continents. These early manatee ancestors had legs and couldn’t simply swim across the ocean; instead, they embarked on a gradual migration over millions of years, which is remarkable given their short legs and reliance on water sources.
During their peak, when the Earth’s climate was significantly warmer and even Greenland had a quasi-tropical climate, sirenians populated all shorelines up to the Arctic Circle. However, as the climate cooled, they were no longer able to survive in the colder waters. Only one species remained able to thrive in the Arctic Circle.
5. The Fascinating Steller’s Sea Cow
Hydrodamalis gigas, also known as Steller’s sea cow, is arguably the most bizarre and intriguing sirenian. Discovered in 1741 and extinct by 1768 due to overhunting, much of what we know about this creature comes from accounts and illustrations. It was unique in comparison to other sirenian species.
For starters, it was massive. Reaching up to 10 meters (33 ft) and weighing as much as 11,000 kilograms (24,000 lb), Steller’s sea cow was about the size of a small whale, far larger than a whole school of manatees combined. Its small head and tiny fins gave it the appearance of a giant overcooked sausage.
According to Wilhelm Steller, the explorer who first encountered the sea cow, only around 2,000 individuals lived in the Bering Sea, mostly around several islands. This creature's habitat was unusually cold for a sirenian, making it an even more curious species. Steller also mentioned that, during winter, their primary food—kelp—became so scarce that by spring, the animals were emaciated.
Soon after, large groups of sailors arrived in the Bering Sea to hunt sea otters, but they also hunted the sea cows relentlessly. Meanwhile, the diminishing sea otter population allowed sea urchins to proliferate uncontrollably, which in turn devoured most of the kelp. These combined factors ultimately led to the sea cows’ extinction. Today, some still wonder if any remnants of this population remain in the cold northern waters, but the scientific community remains doubtful.
4. It Is Illegal To Hug One
All species of manatees and dugongs are considered endangered. As a result, governments around the world have implemented serious conservation measures to protect these creatures. Despite this, their naturally docile personalities continue to put them at risk. In the United States, one of the biggest threats to manatees comes from motorboat propellers, which can cause deep and painful wounds to these slow-moving mammals.
Stress is another significant threat to these animals. In Florida, it is illegal to touch a manatee or remove one from the water. For example, in 2010, a man was charged for hugging a baby manatee because cold stress syndrome could have led to the animal’s death. In 2012, a woman was also charged after riding a manatee, which is punishable by a fine of $500 or 60 days in prison.
Banning the hugging and riding of manatees is just one part of the efforts to safeguard these species. Around the globe, hunting laws have been established to ensure that the remaining manatees and dugongs do not meet the same fate as the extinct sea cow. Additionally, extra caution is necessary when operating motorboats in certain regions.
Thankfully, these protective measures have shown positive results. Recent studies indicate that the manatee population in Florida has seen an increase, while the dugong population in Australia has remained stable over the past few decades. Nonetheless, both species are still classified as endangered.
3. The Relationship Between Sirenians And Humans
The earliest known representation of a sirenian was discovered in a cave painting in Tambun Cave, Malaysia, dating back 5,000 years. This suggests that these creatures held significance for the people of that era.
During the Renaissance, dugongs were regarded as extraordinary beings and were showcased as real mermaids in traveling sideshow exhibitions. Their body parts, including their meat, were highly valued in various Asian cultures. In Arabia, dugong tusks were used to craft sword handles, while in southern China, fishermen avoided hunting the animal, believing it would bring bad luck, a belief also shared by communities in the Philippines.
However, one of the most unexpected references to a sirenian appears in the Old Testament. Some interpretations of Hebrew texts suggest that dugong hides were used to cover the inner sanctum of the Tabernacle, the mobile worship tent that housed the Ark of the Covenant. Yet, this claim is still debated by scholars. The Hebrew word tahash shares a linguistic origin with the Arabic word tucash, which refers to the dugong. Additionally, the archaic scientific name for dugongs is Halicore tabernaculi. If these connections are accurate, it could indicate that dugongs were valued in biblical times.
2. Their Senses And Brains Are Quite Surprising
At first glance, sirenians may appear to be sluggish creatures with unimpressive senses, often earning them the reputation of being slow and dimwitted—hence the nickname sea cows. However, first impressions don’t always tell the full story.
In reality, these animals possess a range of sensory capabilities that help them stay acutely aware of their environment. Moreover, their brains are more complex than one might expect. For example, their faces and bodies are covered in thousands of whisker-like hairs known as vibrissae, which transmit sensory information to their brains, enabling them to navigate using their sense of touch. Some scientists speculate that sirenians can detect low-frequency sounds through these hairs.
Their vision is also quite impressive. They can perceive colors (at least blue and green), and interestingly, they are able to hear with their cheeks. There’s still much more to uncover about their sensory abilities.
When it comes to brain function, sirenians have smooth brains, and they possess the smallest brains of any mammal relative to their body size. However, this doesn’t mean they lack intelligence. A 2006 study by neuroscientist Roger L. Reep revealed that manatees are “as adept at experimental tasks as dolphins, though they are slower and, unlike dolphins, are more difficult to motivate since they don’t have a preference for fish.”
1. They Are Tasty But Off-Limits
In some regions of the world, there is a demand for exotic delicacies, and enthusiasts are eager to try manatee or dugong steaks. The meat is said to have a unique flavor and aroma, though only a few have had the opportunity to taste it. Nevertheless, hunting sirenians is illegal in most places, and the consumption of their parts is strictly prohibited.
While Australia enforces regulations to limit the number of dugongs harvested in order to protect wild populations, some Aboriginal communities are permitted to consume dugong meat due to cultural and heritage traditions. Unfortunately, illegal black markets selling dugong meat still exist in Australia and parts of Asia, continuing to pose a threat to these creatures.
In the United States, manatee protection laws are strict, yet this doesn’t stop some people from fantasizing about enjoying a manatee steak someday. After all, their grandfathers had the legal right to hunt these creatures up until the 1960s, often reminiscing about how good they taste. It’s no surprise that there are individuals contemplating manatee farming as a future business, which could be an interesting idea.
If manatees were farmed, their population could increase as some of them are returned to the wild. However, given that manatees live long lives and breed infrequently, it’s likely that manatee farms would grow at a slow pace.
