In previous posts I have written about different bovine-like aquatic animals found in several Patagonian lakes (Lake bulls). These are definitively bovine because, they phyisically resemble cows and bulls and are also endowed with horns. I also presented some evidence towards the (very faint) possibility that they were actually some kind of bovid species native to Patagonia.
Today I will add some more information on “sea cows”. Which I believe is quite interesting.
Chilean Sea Cows
While reading some new sources on Patagonian lake bulls and cows, I came across the following text, which I will quote in full:
Sometimes certain animals appear in the seas of Arauco [by the region of that name in Chile, between Chiloé and Bio Bio River] that those people call sometimes sea bulls, sometimes sea cows, but which I have not been able to ascertain if they are lamentines or manatees, or if they belong to some other genera; nevertheless I am inclined to believe, based on the vague descriptions that I have acquired that they are manatees or lamentines. The first Spaniards that settled on the large Island of Juan Fernandez caught large quantities of these animals, of whose meat they tastily fed: but the continuous damage they caused them forced them to abandon the vicinity of that island. 
At first I was inclined to believe that they were some kind of seal because, they are no known manatees living in the eastern Pacific Ocean or, in cold waters such as those found in Southern Chile. But, manatees are herbivores and there are plenty of algae along the Patagonian Pacific coastline and, there is evidence that manatees once lived in the area (see map above).
Fossil Chilean manatees
Today there are only four species of the marine mammal order Sirenidae, there was another one, Steller’s sea cow (Hydrodamalis gigas) which regrettably became extinct in the eighteenth century.
All of these sirenians are believed to have originated in the Atlantic Ocean during the Eocene (55.8-33.9 Million years ago). Some of them spread into the Pacific Ocean through the Central American Seaway (a channel that linked both oceans long before North and South America merged at the Isthmus of Panamá. It is marked as the red arrow in the map above). From there they moved north towards California, Alaska and northeastern Asia, and south towards Peru and Chile.
Unlike all other mammals (i.e. seals, walruses, dolphins, seals, etc.) the sirenians are the only mammal herbivores of the seas: they eat algae and sea grass (hence the “cow” part of their name).
Extant sirenians are restricted to warm tropical and subtropical waters because they have a very low metabolism and can not thrive in cold waters. Furthermore, warm, shallow coastal waters favor the growth of the aquatic vegetation that they eat.  Therefore they are not found along the western coast of South America which is subject to the cold water of the Humboldt current that flows along its shores.
But, there was one exception, one species of sea cow that lived in icy North Pacific waters, Steller’s sea cow, which is now extinct.
Going back to South , fossil remains of a sirenian from the Late Miocene have been recovered from sediments of the Bahia Inglesa in Chile at 27° S. This finding are the southernmost remains found on the Eastern Pacific coast (other remains have been found in Peru and California) and they extend the geographic range of these marine beings into the Southern Hemisphere of the Americas. They lived during the Miocene when the global climate was warmer than present and these waters were not as cold as they are nowadays. 
Close by, in Peru there were at least two other species of sea cows, with were unrelated to the extant South American group of manatees. Not surprisingly they were linked to the now extinct Steller’s sea cows of northern North America and to the dugongs of the western Pacific Ocean. These sirenids shared their ecosystem with the "walrus", Odobenocetops and the giant sea sloths, Thalassocnus.
Both sites in Chile and Peru are marked with a red dot in the map above.
Steller´s sea cow ( Hydrodamalis gigas )
This creature was first discovered in 1741, by Captain Bering who found them eating kelp in the cold shallow waters of an island (now named after him), close to Kamchatka Peninsula, Russia. His shipwrecked crew survived the winter by eating them, and they found their meat delicious. News soon spread and all vessels sailing through the area hunted them until there were none left.
These sea cows seem to have been the last survivors (some 1,500 individuals) of a dwindling population that at one time was a widely distributed species. They and their ancestors H. cuestae, Dusisiren dewana, and D. jordani once spanned the Pacific from Japan to California. 
The arrival of humans in America and the Aleutians, and their hunting activities reduced their habitat to Bering Island where, after Captain Bering’s expedition, modern man hunted them to extinction.
Unlike the current warm water sirenians, Steller’s Sea Cow, ate the algae in the freezing waters around the islands where it lived. It was well adapted to the cold Arctic conditions as it had a thich skin (2.5 cm – 1 in.), and an insulating layer of fat between 10 and 23 cm thick (4 -9 in.) . They were enormous and could measure up to 9 m (26 ft) long and could weigh up to 10,000 kg (22,000 lb.).
They lacked teeth but chewed the kelp with two large bony plates that ground the plants, grazing like cows while they bobbed around in the freezing waters (Steller, who described them during Bering’s voyage, said that they could not dive nor submerge as their blubber kept them afloat). Docile creatures that apparently lacked predators, they were easily hunted and killed.
Even though the last sea cow was killed in 1768 (barely twenty seven years after it had been discovered by science), there have been alleged sightings of sea cows since then. The more recent ones are from a whaling boat in 1962 that saw a herd of them  and in 2006 a sighting in Washington state, U.S.
The coast of Southern Chile, from Chiloé to Cape Horn has abundant algae. One variety known as cochayuyo or cachiyuyo (Durvillaea antarctica), is an edible seaweed which is also found in New Zealand and the South Atlantic. It can reach a length of 15 m (49 ft.) . There are also submarine forests of dense groups of Giant Kelp, Macrocystis. pyrifera, which can be found up to depths of 20 m (650 ft.), and occasionally up to 80 m (262 ft.) deep.
These could provide the food for the “sea cows” of the “Arauco sea”. Perhaps they did not become extinct in Chile and, like Steller’s sea cows, they adapted to a colder aquatic environment with no predators. Arrival of modern man towards the end of the last Ice Age would have placed them in a situation similar to their north Pacific relatives. Perhaps they sought safety at Juan Fernandez Islands which are about 600 km (373 mi.) from Chile (approx. 33ºS; 79ºW) from where they were displaced by the relentless hunting after their discovery in the XVIth century.
I have not been able to find any data on the aquatic resources (i.e. algae) at these islands, because, if the sea cows lived there, they had to have seaweeds to graze on.
If they somehow survived in the fjords and channels of Southern Chile, they could have originated the belief in “sea cows” such as the one that I mention below:
SEA COW: Animal of fabulous beauty that travels about the channels seeking bulls to seduce. It is considered an aquatic version of a bovine, whose legs are flippers, fat of curved horns and fiery eyes. It bewitches bulls and mates with them with such passion that the animal is left impotent and nostalgic….
Steller sea cows are indeed fat and large, but, they lack horns. So, I wonder if it was an embellishment added by the locals, or, simply another creature and not a genuine sea cow. The question remains open.
It is interesting to point out however that according to French naturalist Cuvier :
Which is remarkably similar to what Father Diego de Rosales’ wrote about the mermaid, Pincoya that had been seen several times in the sea by Chiloé in 1632:
a beast that came close to the shore, which surging out of the water displayed a head, face and woman’s breasts, with long fair and loose hair or mane. It carried a child in its arms. When it submerged they noticed that it had a tail and back of a fish, covered with thick scales like small shells.
See also (in the same post), Byron's description of a merman in the Chonos islands in 1741 that had, "an appearance like that of a man swimming half out of the water" .
Both are very similar to Cuvier's description.
Could these be sightings of a sea cow?
 Estala, Pedro, (1798). El viagero universal o Noticia del mundo antiguo y nuevo. Imprenta de Villalpando. pp. 179
 Sirenian International
 Giovanni Bianuccia, Silvia Sorbia, Mario E. Suárez and Walter Landinia. The southernmost sirenian record in the eastern Pacific Ocean, from the Late Miocene of Chile. C. R. Palevol 5 (2006) 945–952. doi:10.1016/j.crpv.2006.06.001.
 Dietz, Tim, (1992). The call of the siren: manatees and dugongs.Fulcrum Publishing. pp.102.
 Colman, Loren, (2006). Steller’s sea cow sighting? Cryptomundo. 16.09.2006.
 Image credits: Mooney, Sharon, (2002). Sirenian Evolution. Howard University. Academic Press, 20002.
 Renato Cárdenas Alvarez. (1997) El Libro de la Mitología de Chiloé. Anaquel Austral. Ed. Virginia Vidal. Santiago : Editorial Poetas Antiimperialistas de América. 15.09.2005.
 Cuvier, Georges, (1832). The animal kingdom: arranged in conformity with its organization. G. & C. & H. Carvill, pp 116.
 De Rosales, D., (1877). Historia general de el Reyno de Chile. Valparaiso: El Mercurio. v. i, ii. v. 1. pp. 308- 309.
 Byron J., (1996). Naufragio en las costas patagónicas. Buenos Aires: Ediciones del Sol. pp. 63.
Steller's Sea Cow Hydrodamalis gigas.
Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia2010 International Year of Biodiversity Copyright 2009-2010 by Austin Whittall ©