Scutisorex somereniarmored shrew(Also: hero shrew)

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Geographic Range

The range of Scutisorex somereni, the hero shrew, is restricted to the forest belt in Africa. The countries located within the forest belt range from southwestern Uganda, eatern Zaire, and to northern Rwanda.

Habitat

Swamps and waterlogged areas are common in the parts of Africa occupied by this species and have specialized flora and fauna (Kingdon, 1971). Hero shrews prefer areas of trees, palms, and dense undergrowth at low elevation.

Physical Description

"The hero shrew is a large gray shrew with a thick woolly fur (Kingdon 85)." The head and body lengths range from 120 to 150 mm, and the tail length can vary from 68 to 95 mm. The weight is also variable between 30 to 115 g. The pelage is long, thick and coarse. According to Ducommun the hairs of shrews in general function as complex protective structures. The pelage of the hero shrew consists of sensitive tactile and projectile components. It is hypothesized that the projectile, rigid hairs help to disperse scent (Ducommun et al. 630). "The armored shrew, Scutisorex somereni, is an African giant shrew with long fur. The well-developed shield shows modifications for which no plausible explanation is yet available. This big shrew is well known for other enigmatic structures, namely the vertebrae with lateral and ventral interlocking spines and eleven instead of five lumbar vertebrae, a condition no recorded in any other mammal (Ducommun et al. 638)."

The hero shrew is one of the most modified among the vertebrates (Kingdon 1974). The spine is spectacular and is equipped with extra joints that allow for flexibility. The spine has been described as a large bony buttress, which is key to its unusual strength. The size, shape and articulation of the lumbar region is considerabley altered from other members of the insectivore family. The spine structure reduces compression along the postcranial body. The hero shrew's spinal column has the ability to withstand extreme loading of weight. Each vertebrae between the rib cage and the hips is a corrugated cylinder. The spine has a series of complex interlocking tubercles that articulate with the previous and succeeding vertebrae. The series of tubercles have also been called the scaling morphology. This scaling morphology reduces the compression along the postcranial body allowing the hero shrew to withstand the weight of a 160 pound man. Currently there is not a satisfactory ecological, behavioral, or morphological explanation for such a super structured spine.

Although the spine is robust, the rest of the postcranial vertebral column is not especially fortified. The morphology of the axial skeletion is approppriate for handling large loads, but the appendicular skeleton is not (Cullinane el al. 449). The difference between the shrew's strong spine and the rest of its limbs is striking. The limbs, according to Cullinane et al, do not exhibit a significant difference in robustness when compared to other small mammals.

The mass of the spine accounts for nearly 4 percent of the hero shrew's body weight. Comparing the spinal column mass to body mass ratio of other small mammals, we find that for small mammals the spinal column to body ratio ranges only between .5 and 1.6 percent. This is a significant difference that is not understood fully. The unusual spinal morphology was not recognized as an anomaly at first because early investigation of the hero shrew consisted solely of reviewing just the skull and the skin characteristics. Not until 1917 when a researcher named Allen found a preserved specimen, at the American Museum, did the spine begin to be investigated.

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    30 to 115 g
    1.06 to 4.05 oz

Reproduction

There is little information on the reproduction of the hero shrew. Ther breeding behavior has not been observed. The only mention of reproduction is an account that two lactating females were caught in May and three sexually inactive animals were caught in the same month (Kingdon 91).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual

Behavior

The hero shrew's back is used to rub scents on objects and possibly on other shrews. The hero shrew is a compulsive scent marker, according to Jonathan Kingdon in Vol I. The scent of the lateral glands seem to act as an intra-specific repellent in some species of shrew (Crowcroft, 1957; Pearson 1946). When this shrew is scenting an area, their bodies are flexed into unusual contorted positons (Kingdon, 1971). Once a hero shrew is trapped and placed into its dwelling the shrew will mark its territory prior to any other activity. Secretions from the hero shrew's scent glands is very pungent and can visibly stain the normally gray fur of the hero shrew yellow.

In an attempt to understand the super spinal column, Cullinane constructed a habitat out of plastic tubes and boxes. He recorded all of the shrew's movements on video tape. When he began upon reviewing the chronological account of this shrew movements he found that the hero shrew could turn 180 degrees in a tube that was just a little wider than the animal itself. This is amazing because normally in lower mammalian species the spine is very stiff. The stiffness helps to accommodate forces generated by the hind legs. One hypothesis regarding the flexibiltiy of the hero shrew is that the spine was emphasized while the musculature was reduced.

Communication and Perception

Food Habits

A report by Kingdon suggests that hero shrews prefer an environment that is dense in undergrowth of wild ginger and arrowroot. Although this would suggest that the hero shrew is an herbivore, it is not. In the field, Land recorded a variety of food items in the stomachs of trapped Scutisorex somereni including insects, caterpillars, earthworms, and the remain of frogs. In captivity hero shrews also consume mammal meat if given the opportunity.

Economic Importance for Humans: Positive

The hero shrew is important locally. The tribe's people believe that any part of the hero shrew will act as a tailsman to save them from peril.

Economic Importance for Humans: Negative

None

Conservation Status

Researchers have found the hero shrew in Africa but the population has not been evaluated.

Other Comments

Natives of the Congo region, the Mangbetu, believe that the hero shrew possesses magical powers. This shrew is believed to invoke powers of bravery and immunity from wounds. Parts of the hero shrews are worn as tailismans bestowing invincibility in war. Naturalist Herbert Lang and James Chapin wrote:

"The Mangbetu gave it a name meaning 'hero shrew'. Those engaging in warfare or setting out upon an equally dangerous enterprise such as hunting elephants are anxious to carry along even a fraction of the ashes of this shrew. Though only worn somewhere about their body, they believe that neither spears nor arrows, nor any kind of an attack can seriously injure them, much less bear them down....Whenever they have a chance they take great delight in showing to the easily fascinated crowd its extraordinary resistance to weight and pressure. After the usual hubbub of various invocations, a full-grown man weighing some 160 pounds steps barefoot on the shrew. Steadily trying to balance himself upon one leg, he continues to vociferate several minutes. The poor creature seems certainly to be doomed. But as soon as his tormentors jump off, the shrew after a few shivering movements escapes and is none the worse for this mad experience and apparently in no need of the wild applause and exhortations of the throng (Allen, 1917)."

Contributors

Jani Hatchett (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

World Map

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.

chemical

uses smells or other chemicals to communicate

endothermic

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.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

References

Allen, .. 1917. The skeletal characters of Scutisorex. Bulletin of the American Museum of Natural History: American Museum of Natural History.

Crowcroft, P. 1957. The life of Shrews. London: Reinhardt.

Cullinane, D., D. Aleper. March 1998. The functional and biomechanical modifications of the spine of Scurisorex somereni, the hero shres: spinal musculature. Journal of Zoology, 224 (3): 453-452.

Cullinane, D., D. Aleper, J. Bertram. March 1998. The functional and biomechanical modifications of the spine of Scutisorex somereni, the hero shrew: skeletal scaling relationships. Journal of Zoology, 244 (3): 447-452.

Ducommun, M., F. Jeanmairebesancon, P. Vogel. September 1994. Shield Morphology of Curly Overhair in 11 General of Soricidae (Insectivora, Mammalia). Revue Suisse De Zoologie, 101:(3): 623-643.

Kingdon, J. 1971. East African Mammals an Atlas of Evolution in Africa. London: Academic Press.

Kingdon, J. 1974. East African Mammals an Atlas of Evolution in Africa Volume II Part A. London: Academic Press.

Kingdon, J. 1971. "East African Mammals an Atlas of Evolution in Africa Volume I" (On-line).

Moreau, R. 1966. The bird fauna of Africa and its islands. London: Academic Press.

Nowak, R. 1999. Walker's Mammals of the World, Volume I. Baltimore and Londaon: The Johns Hopkins University Press.

Pennisi, E. January 12, 1996. Superhero Shrew. Science, 271:149: 149.