Weevil
| Weevil | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Dominican sand weevil ( Solenodon paradoxus ) |
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| Systematics | ||||||||||||
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| Scientific name of the family | ||||||||||||
| Solenodontidae | ||||||||||||
| Gill , 1872 | ||||||||||||
| Scientific name of the genus | ||||||||||||
| Solenodon | ||||||||||||
| Brandt , 1833 |
The slot weevils (Solenodontidae) are a family of mammals from the order of the insectivores (Eulipotyphla). These animals are reminiscent of large shrews and inhabit only the Caribbean islands . The family includes one genus ( Solenodon ) with two species, the Dominican or Haiti sand weevil and the Cuban sand weevil , both of which are threatened. Two other species are extinct.
features
General
By their physique, slot weevils are reminiscent of huge, stocky shrews. They reach a head body length of 28 to 39 centimeters and a tail length of 18 to 26 centimeters. The weight of adult animals is around 0.8 to 1 kilogram. The coat color varies from reddish-brown to black, whereby the Cuban slit weevil is darker in color and has a softer and longer coat than the Dominican. The tail and legs are hairless in both species.
As with all insectivores, the feet each end in five toes with claws. The claws of the front paws are significantly longer and more curved than those of the rear paws, the thumb and big toe cannot be opposed . The animals have glands in the armpit and groin; these secrete a secretion, the smell of which is described as "goat-like".
Head and teeth
The most striking feature of the head is the trunk-like, elongated nose, which is supported by a trunk bone ( praenasale ). The nostrils point to the side. As with many insectivores, the skull is narrow and elongated, the eyes are comparatively small, and the partially hairless ears protrude from the fur.
The dentition , is provided, as in all insectivora, with pointed cusps and sharp melting strips. The front incisor is enlarged and there is a gap ( diastema ) between it and the other teeth . The tooth formula is I 3/3 - C 1/1 - P 3/3 - M 3/3, so you have 40 teeth in total. The young animals are not yet born with permanent teeth, but have functional milk teeth .
Along with the water shrew and the slow loris ( Nycticebus ), slot weevils are the only poisonous higher mammals . They produce a neurotoxin in the salivary gland of the mandible that allows them to overwhelm relatively large prey. The poisonous saliva is directed into the wounds of the prey through a deep groove on the inside of the second lower incisor.
distribution and habitat
Sand weevils are endemic to the Greater Antilles , the Cuban sand weevil lives in Cuba and the Dominican sand weevil in Hispaniola ( Haiti and Dominican Republic ). The extinct species are also only known from these two islands. The habitat of these animals is primarily forests, but they are sometimes found in the bushland near plantations.
Way of life
The animals are predominantly nocturnal. They are soil dwellers and lead a partially subterranean way of life. To sleep they retreat into crevices, hollow tree trunks, holes in the ground or self-dug burrows, but they do not build nests outside of the mating season. Sometimes they also create complex tunnel systems under the ground, which they use as resting places and sometimes also for foraging. On the surface they move in a rather clumsy, waddling walk, but they can run very quickly in the event of a threat.
Weevils emit high click sounds in the range from 9000 to 31000 Hz . As with the shrews , these sounds seem to serve the purpose of echolocation , since weevils have only small eyes and see poorly.
Little research has been done into social behavior. At least the Dominican weevils are known to live in small groups and that up to eight animals share the same shelter. Mature animals often stay in the same den or in close proximity to their parents.
food
The foraging for food takes place either underground or on the surface of the earth, while weeping weevils rummage through the soil with their snout. Sometimes they also use their claws to tear up hard soil or tree bark.
Slotted weevils are omnivores , but feed primarily on carnivore . Their diet consists primarily of invertebrates such as bipedes , insects and earthworms , but they also eat vertebrates such as small reptiles . To a lesser extent, they also consume fruits and other plant material.
Reproduction
Little is known about reproduction. The females have a pair of teats in the groin region. The pairing is likely to be aseasonal (not tied to the seasons) and occur irregularly. The female can give birth to one or two young animals up to twice a year after a gestation period of around fifty days. Before birth, it builds a nest in which the newborns spend their first weeks of life. They weigh around 40 to 55 grams at birth and are initially naked and blind. They are weaned at around 75 days.
The maximum known age of a sand weevil in human care was eleven years; life expectancy in the wild is unknown.
threat
Before the arrival of humans on their home islands, the sand weevils had hardly any natural enemies and therefore did not develop any defensive behavior. Since domestic dogs , house cats and small mongooses were introduced, stalking by these animals has been the greatest threat. In addition, their habitat is destroyed by conversion into agricultural land and settlement areas.
The Cuban sand weevil was already considered extinct in the 1950s, before some specimens were rediscovered in the eastern parts of Cuba since the 1970s. Nevertheless, the species is considered rare. The Dominican sand weevil, on the other hand, was considered to be relatively common until the 1960s, although the population in Haiti had declined significantly. Since that time, however, the populations of this species have also started to decline.
Both species are now pushed back into small, impassable regions. The IUCN lists both sand weevil species as endangered and fears a further decline in populations.
Systematics
External system
The slot weevils are integrated into the order of the insectivores (Eulipotyphla). This order has a taxonomically highly controversial history; again and again taxa were incorporated or removed. The molecular genetic studies also do not provide a clear result, so that the parentage relationships within this group remain controversial. The closest relatives of the slot weevils were the Caribbean shrews (Nesophontidae), a group of shrew- like animals that is now extinct and spread in the Greater Antilles until the 2nd millennium AD.
It is possible that the sand weevil and the Caribbean shrew represent the remnants of an earlier - possibly already since the Mesozoic era - widespread group of insectivores on the American continent, which after their relatives on the mainland became extinct on the Caribbean islands. So far, however, there are no fossil finds that could confirm this theory. However, an analysis of the mitochondrial DNA of the Dominican sand weevil revealed that the last common ancestor of the sand weevil and all other recent insectivores lived in the Campanium (Upper Cretaceous) about 73.6 to 78 million years ago , i.e. before the mass extinction on the Cretaceous-Paleogene border .
Internal system
The sand weevil family consists of four species, including two extinct, all of which are included in the genus Solenodon .
- The Cuban sand weevil ( Solenodon cubanus ) lives in Cuba and is the darker and longer-haired of the two species still alive today. Sometimes it is listed in its own genus, Atopogale .
- The Dominican or Haiti slitter weevil ( Solenodon paradoxus ) has a shorter, rather lighter coat and is native to Hispaniola .
- Solenodon arredondoi is extinct. The species was native to Cuba and, with a head body length of 45 to 55 centimeters and an estimated weight of 1.5 to 2 kilograms, is significantly larger than the two species still alive today. The date of extinction of this species is unclear, but it survived at least until the arrival of the Indians in Cuba.
- Solenodon marcanoi is also extinct. This species in turn lived on Hispaniola and was smaller than the first two species mentioned. Remains of this species have been found along with rat bones , suggesting that it still existed at least until the arrival of Europeans. Sometimes it is listed in its own genre, Antillogale .
literature
- Gerhard Storch : Lipotyphla, insect eater. In: Wilfried Westheide , Reinhard Rieger (Ed.): Special Zoology. Volume 2: Vertebrates or Skull Animals. Spektrum Akademischer Verlag, Heidelberg et al. 2004, ISBN 3-8274-0307-3 , pp. 514-524.
- Ronald M. Nowak: Walker's Mammals of the World. 2 volumes. 6th edition. Johns Hopkins University Press, Baltimore MD et al. 1999, ISBN 0-8018-5789-9 .
- Don E. Wilson , DeeAnn M. Reeder (Eds.): Mammal Species of the World. A taxonomic and geographic Reference. 2 volumes. 3. Edition. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 .
Individual evidence
- ↑ Solenodons . animal.discovery.com. Archived from the original on August 6, 2013.
- ↑ Kirill Grigorev et al. Innovative assembly strategy contributes to understanding the evolution and conservation genetics of the endangered Solenodon paradoxus from the island of Hispaniola. GigaScience, March 16, 2018; doi: 10.1093 / gigascience / giy025
- ↑ Adam L. Brandt, Kirill Grigorev, Yashira M. Afanador-Hernández, Liz A. Paulino, William J. Murphy, Adrell Núñez, Aleksey Komissarov, Jessica R. Brandt, Pavel Dobrynin, J. David Hernández-Martich, Roberto María, Stephen J. O'Brien, Luis E. Rodríguez, Juan C. Martínez-Cruzado, Taras K. Oleksyk, Alfred L. Roca. Mitogenomic sequences support a north – south subspecies subdivision within Solenodon paradoxus. Mitochondrial DNA Part A, 2016; 1 DOI: 10.3109 / 24701394.2016.1167891
Web links
- Endangerment level of the species Solondon cubanus , paradoxus and marcanoi on the IUCN Red List
- Haiti's little ghosts Article by Sven Stockrahm in: Zeit Online , January 13, 2009
- Video on Spiegel Online , December 11, 2009
