Caribbean monk seal characteristics, habitat, causes of extinction

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Egbert Haynes

The Caribbean monk seal (Monachus tropicalis) was a species that belonged to the Phocidae family. It is currently considered extinct, mainly due to the over-exploitation suffered to obtain oil from its body fat. It was mainly distributed in the waters of the Caribbean Sea and east of the Gulf of Mexico.

This species can grow to around 270 centimeters, although it is believed that there may have been individuals reaching lengths of up to 325 centimeters. Regarding its coloration, it was dark dorsally, with brown or black tones. In contrast, the belly had a yellowish-white color.

Caribbean monk seal. Source: New York Zoological Society. [Public domain]

The Caribbean monk seal was one of the three species of monk seals in the world. However, the relationship between this and the Mediterranean and Hawaiian monk seals was not well defined..

In recent studies, scientists clarified the evolution of the Monachus tropicalis. For this they analyzed DNA samples and compared the skull of the three species. The results showed that the Caribbean species was more closely related to the Hawaiian monk seal than to the Mediterranean species..

Additionally, experts note that the split between Hawaiian and Caribbean monk seals occurred around 3 to 4 million years ago. At that time, the Panamanian isthmus closed the connection between the Pacific and Atlantic oceans, being a decisive factor in the divergence of both pinnipeds (carnivorous mammals).

Thus, the profound morphological and molecular differences between the New World and Mediterranean species gave rise to a new genus: Neomonachus. This includes the Hawaiian seal and the Caribbean monk seal..

Characteristics

Body

The body of the Caribbean monk seal was relatively large, robust, and long. It had a thick layer of fat, in the form of a hood, that surrounded the neck. The females had two pairs of breasts.

Compared to the size of the body, the fore fins were short and had well developed nails. In relation to the rear fins, these were thin, with simpler nails.

Size

In this species there was sexual dimorphism, the female being smaller than the male. In the case of the latter, its length could be between 1.8 and 2.7 meters, although it could reach 3.25 meters in length. Body mass ranged from 250 to 300 kilograms.

Head

The head had a rounded shape, highlighting an extended and wide muzzle. On the face, it had two large eyes, light reddish-brown in color. These were widely separated from each other. As for the nostrils, their opening was focused upwards. Lacked external ears.

Coloration

The Caribbean monk seal had a stiff, short coat. Regarding their coloration, there was no difference between the male and the female. The dorsal region of the body was dark. Thus, it varied from brown to black, with slight grayish tones, due to the fact that the end of the hairs could have a lighter tone..

On the other hand, algae of various species grew on the fur. This added greenish tones to her overall look. On the sides of the body, the color becomes lighter until it reaches the ventral area, which was white or yellowish gray. In some species, this area exhibited certain dark spots.

In relation to the face, the terminal end of the snout and the areas around the upper and lower lip were yellowish white. As for the vibrissae, they were generally smooth and white, although it could also have dark ones, which were short.

There was a notable difference between the tones of the adult and those of the youth. In the case of adults they were usually lighter, while in juveniles it had a yellowish back, in contrast to the ventral area, which was ocher. At the terminal end of the muzzle, a dark central area stood out.

Habitat and distribution

Distribution

The Monachus tropicalis It was mainly distributed in the Caribbean Sea and to the northwest of the eastern part of the Gulf of Mexico. Thus, it was located on various islands, cays and reefs, including the Bahamas, the Florida Keys and the Lesser and Greater Antilles..

It also lived in the Yucatan Peninsula and to the southeast, along the entire coastal zone of Central and South America, reaching as far east as Guyana. The northernmost record occurred in Georgia, in the southeastern United States..

Among the countries where the Caribbean monk seal was found are the Bahamas, Antigua and Barbuda, Belize, Cuba, Costa Rica, Dominica, Guadeloupe, the Dominican Republic, Haiti and Puerto Rico. In addition, it spread in the United States (Georgia and Florida), Jamaica, Mexico (Yucatán and Veracruz) and in the Caribbean islands of Honduras and Nicaragua..

In the United States, this species was sighted for the last time in 1932, off the coast of Texas. Later, in 1952, specialists confirmed the presence of a small group on Serranilla Island, located in the Caribbean Sea..

Habitat

This species lived in temperate, tropical and subtropical waters, in regions with sandy or rocky coasts. This preference is due to the fact that these areas were used by this marine mammal as a place to take refuge, rest and reproduce..

Likewise, they inhabited sandy beaches, islands and atolls. Occasionally they were able to visit the deeper waters and continental coasts.

Causes of extinction

Caribbean monk seals were first identified in 1494, on the second voyage of Christopher Columbus. These animals were hunted for their meat. After the European colonization, which occurred between 1700 and 1900, these fócids suffered overexploitation, mainly to obtain their fat and skin..

Henry W. Elliott [Public domain]

Other reasons for its capture were for food, for scientific studies and for collections in zoos. In addition, the seal was highly valued by the fishing industry..

Thus, the fat was processed, obtaining oil. This was used to lubricate and to cover the bottom of the boats. Also, it was used to make clothing, bags, straps and linings for trunks..

The high demand for by-products of the Monachus tropicalis encouraged hunters to kill them. Human pressure caused the populations of this animal to decline significantly, which ultimately led to the extinction of the species.

Dam shortage

The second factor that affected the disappearance of the Caribbean monk seal was overfishing of the reefs, one of its natural habitats. This caused that, not being able to have fish and mollusks, the animal could not feed.

This situation persisted for a long time, causing a decline in the physical state of the pinniped, so it could not even reproduce. As a last consequence, the death of the animal occurred.

Actions

The first legal protection was in 1945, when the species was included in the Jamaica Wildlife Act. Likewise, since 1973, the Monachus tropicalis was under the protection of the IUCN.

Surprisingly, the vast majority of protectionist actions for this species were taken when it was probably already extinct..

Reproduction

The natural history of the Caribbean monk seal is very little known. This is mainly due to the fact that when it became extinct there were few investigative works that provided more details about its development..

However, experts point out that it may have reached sexual maturity between 4 and 8 years, as occurs in other pinnipeds. Likewise, the reproductive season had a wide range, typical of the species of the family to which it belongs..

However, there may have been months in which the mating season peaked. Thus, those that lived in Mexico, reproduced in greater proportion during the first days of December.

In relation to gestation, the female developed a single offspring. It is about 1 meter long, weighing between 16 and 18 kilograms. In terms of fur, it was long and smooth, shiny black. This tonality lasts for about a year. The young man's whiskers were dark.

Feeding

The Caribbean monk seal could have foraged in lagoons and shallow reefs. Their diet consisted of various pelagic species, including eels, lobsters, octopus, and fish..

Regarding the feeding strategy, this species used drilling, for which it captured its small prey using its small and sharp teeth. Thus, after a penetrating bite, the seal can easily swallow the animal.

This eating method is supported by certain mandibular and cranial characteristics. Thus, the Monachus tropicalis had an enlarged infraorbital foramen, an elongated rostrum, and a thickening of the dorsal ventral area of ​​the skull.

In addition, it had a thin mandibular coronoid process, while the mandible was thicker dorsoventrally..

On the other hand, this species combined nutrition by drilling with suction. In this way, it opportunistically captured its prey..

Behaviour

Experts note that the Caribbean monk seal had patterns of high activity during dusk and dawn. They also describe it as a not very aggressive species, which moved very slowly on land. This particularity was taken advantage of by man, since it greatly facilitated his capture.

When he was in the resting areas, he could have formed large groups, consisting of between 20 and 40 seals. Said groupings were organized by age and by the stage of development in which the animal was..

References

  1. Dirk-Martin Scheel, Graham J. Slater, Sergios-Orestis Kolokotronis, Charles W. Potter, David S. Rotstein, Kyriakos Tsangaras, Alex D. Greenwood, Kristofer M. Helgen (2014). Biogeography and taxonomy of extinct and endangered monk seals illuminated by ancient DNA and skull morphology. Recovered from ncbi.nlm.nih.gov.
  2. Wikipedia (2020). Caribbean monk seal. Recovered from en.wikipedia.org.
  3. Lowry, L. (2015). Neomonachus tropicalis. The IUCN Red List of Threatened Species 2015. Recovered from iucnredlist.org.
  4. Lowry, Lloyd. (2011). Book Review: Caribbean Monk Seals: Lost Seals of the Gulf of Mexico and Caribbean Sea. Recovered from researchgate.net.
  5. Maas, P.H.J. (2017). Neomonachus tropicalis (Caribbean Monk Seal). Recovered from petermaas.nl.
  6. Sarah S. Kienle, Annalisa Berta (2016). The better to eat you with: the comparative feeding morphology of phocid seals (Pinnipedia, Phocidae). Recovered from ncbi.nlm.nih.gov.
  7. Davies, L. (2008). Monachus tropicalis. Animal Diversity Web. Recovered from animaldiversity.org.
  8. National Oceanic And Atmospheric Administration. (2008). Caribbean Monk Seal Gone Extinct From Human Causes, NOAA Confirms. Recovered from sciencedaily.com.

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