All members of genus Caenolestes are found within the northern Andes Mountains. Blackish shrew opossums ( ) are found within two ranges, western Columbia as well as north central Ecuador. Ranges of blackish shrew opossums and their close relative, gray-bellied shrew opossums (Caenolestes caniventer), overlap, both species are found primarily in the Pacific slopes of the Andes Mountains. (Albuja and Patterson, 1996; Lunde and Pacheco, 2003; Patterson and Gomez-Laverde, 2008)
Blackish shrew opossums reside in subtropical and montane forests of the Andes Slopes. They are found in several elevations. In their Columbian range, they can be found from 1,800 to 3,800 meters. In their Ecuadorian range they are typically found from 1,100 to 2,980 meters, but have been found as high as 4,100 meters. These animals prefer cool wet areas and create channels under root systems, along streams in wet grasslands. (Albuja and Patterson, 1996; Barnett, 1991; Patterson and Gomez-Laverde, 2008; Tate, 1931; Timm and Patterson, 2008)
- Range elevation
- 1,100 to 4,100 m
- to ft
Blackish shrew opossums are marsupials; they are somewhat shrew-like in appearance, with elongated faces. Their appearance is very similar to their close relative, gray-bellied shrew opossums (Caenolestes caniventer). Both have very coarse, dark dorsal pelage, with relatively long fur (about 10 mm long); however, blackish shrew opossums have larger molars. This species has a total body length of about 256 mm, including a tail length of about 124 mm and they weigh about 40 grams. (Lunde and Pacheco, 2003; Osgood and Herrick, 1921; Tirira, 2007)
In general, members of family Caenolestidae can be distinguished from other marsupial groups by their unique dentition. They have a reduced number of incisors and their lower middle incisors are large and have a forward slope. The dental formula for genus Caenolestes is: I 4/3, C 1/1, P 3/3, M 4/4, 46 teeth total. Their tail is long, about as long as their body, and appears rat-like and hairless, although it is covered in white fur. While their tail is not prehensile, it is used for support while they climb. Shrew opossums have short robust limbs, each containing 5 digits; their middle 3 digits are shorter than the outside 2. Their humeri are extremely heavy; in comparison, their femurs are relatively slender. Members of family Caenolestidae have unusual lip flaps, which may function as a method of preventing debris from interfering with their whiskers or they may help prevent ingestion of unwanted debris. Similar to other marsupials, Caenolestid females have 2 uteri and 2 vaginas. Members of genus Caenolestes lack a pouch but do have 4 mammae, 2 on either side of their abdomen. (Albuja and Patterson, 1996; Lee and Cockburn, 1985; O'Connell, 2006; Osgood and Herrick, 1921; Tirira, 2007)
Common shrew opossums (Caenolestes obscurus), a close relative of blackish shrew opossums, show evidence of a low metabolic rate, based on their body temperature (35.4° C), their body weight (about 40 g), their cool habitat and their thick fur coat. This species shows no evidence of entering torpor. (McNab, 1978)
- Sexual Dimorphism
- male larger
- Average mass
- 40 g
- 1.41 oz
- Average length
- 256 (including the tail) mm
There is currently little information available regarding the mating system of blackish shrew opossums.
Female blackish shrew opossums lack a marsupium; however, immature individuals may have an undeveloped fold of skin that they lose before reaching maturity. Females have 4 mammae available for their young to nurse. Evidence suggests that Caenolestid females have the same number of ova as mammae, unlike family Didelphidae. In support of that notion, a female was found pregnant with 3 embryos, 2 in the right uterus and 1 in the left. These animals likely have one annual breeding season from February to August. (O'Connell, 2006; Osgood and Herrick, 1921; Tirira, 2007; Tyndale-Biscoe and Renfree, 1987)
- Key Reproductive Features
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- Breeding interval
- Members of family Caenolestidae likely breed once per year.
- Breeding season
- The breeding season of family Caenolestidae is likely between February and August.
No information is currently available regarding this species.
There is currently no information on the longevity of blackish shrew opossums.
Members of genus Caenolestes are solitary; they are primarily active during the early evening and at night. They are terrestrial, but they are also adept climbers. During the day, these animals stay in tunnels under tree roots. When they are active, they travel through paths in dense vegetation. (O'Connell, 2006; Patterson and Solari, 2008; Timm and Patterson, 2008; Tirira, 2007)
There is currently no information available about the individual home range of blackish shrew opossums.
Communication and Perception
Members of family Caenolestidae have very small eyes and poor eyesight. Their unusual lip flaps have the hypothesized function of clearing debris from their sensitive vibrissae, but they may merely function as a method of preventing the ingestion of unwanted debris. Their somewhat primitive brains have enlarged olfactory bulbs, which could indicate an enhanced sense of smell. When they are startled they attempt to hide and they hiss when cornered. Caenolestids are not noted for frequent production of sound, however, captive individuals may make several sounds including whistles, bird-like screams, rat-like squeaks and drawing air through their incisors. (Hume, 1982; Kirsch and Waller, 1979; O'Connell, 2006; Vaughan, et al., 2011)
Members of genus Caenolestes are opportunistic feeders. Their stomach contents indicate that they are primarily insectivores. Ingested invertebrates include beetles, crickets, butterfly larvae, centipedes, grasshoppers, spiders, and earthworms. A smaller proportion of their diet is composed of vegetation, fruit and small vertebrates including juvenile mice. They forage for food in moss and leaf litter. When they find a food item, they manipulate and consume it with their forepaws, from a semi-seated position. As Caenolestids shear their food with their incisors, they produce a clicking sound. (Barkley and Whitaker, 1984; Patterson and Solari, 2008; Timm and Patterson, 2008; Tirira, 2007)
- Animal Foods
- terrestrial non-insect arthropods
- terrestrial worms
- Plant Foods
There is currently little information regarding the predation of blackish shrew opossums. However, there are several carnivores known to inhabit a similar range and prey upon small mammals, such predators include Andean Mountain cats (Leopardus jacobita), pampas cats (Leopardus colocolo), culpeo foxes (Lycalopex culpaeus) and cougars (puma concolor), among others. (Lucherini, et al., 2009)
Blackish shrew opossums have an insectivorous diet. Likewise, Caenolestids are often plagued by lice of the genus Cummingsia. Interestingly, Australian marsupials are also affected by similar lice, related to the family level. Caenolestids may also become infested with South American hard ticks (Ixodes jonesae). (Barkley and Whitaker, 1984; Lee and Cockburn, 1985; Tirira, 2007; VanZolini and Guimaraes, 1955)
- lice (Cummingsia)
- South American hard ticks (Ixodes jonesae)
Economic Importance for Humans: Positive
Due to their human-inaccessible habitat, there has been very little study of these animals. Likewise, there has been very little interaction between human and shrew opossum populations. They may, however, serve as a control of insect populations. (Kirsch and Waller, 1979)
Economic Importance for Humans: Negative
There are no known negative effects of blackish shrew opossums on human populations.
Blackish shrew opossums are currently listed as vulnerable on the IUCN Red List of threatened species. This species is susceptible to habitat fragmentation, specifically in the northern portion of their range. (Patterson and Gomez-Laverde, 2008)
Leila Siciliano Martina (author), Animal Diversity Web Staff.
living in the southern part of the New World. In other words, Central and South America.
uses sound to communicate
- bilateral symmetry
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
active at dawn and dusk
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
An animal that eats mainly insects or spiders.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
- native range
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
- seasonal breeding
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
Living on the ground.
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
Barkley, L., J. Whitaker. 1984. Confirmation of Caenolestes in Peru with information on diet. Journal of Mammalogy, 65:2: 328-330.
Barnett, A. 1991. Records of the grey-bellied shrew opossum, Caenolestes caniventer and Tate's shrew opossum, Caenolestes tatei (Caenolestidae, Marsupialia), from Ecuadorian montane forests. Mammalia, 55:3: 443-445.
Hume, I. 1982. Digestive physiology and nutrition of marsupials. Cambridge: Cambridge University Press.
Kirsch, J., P. Waller. 1979. Notes on the trapping and behavior of the Caenolestidae (Marsupialia). Journal of Mammalogy, 60:2: 390-395.
Lee, A., A. Cockburn. 1985. Evolutionary ecology of marsupials. Cambridge: Cambridge University Press.
Lucherini, M., J. Reppucci, R. Walker, M. Villalba, A. Wurstten, G. Gallardo, A. Iriarte, R. Villalobos, P. Perovic. 2009. Activity pattern of segregation of carnivores in the high Andes. Journal of Mammalogy, 90:6: 1404-1409.
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