Lowland streaked tenrec
|Lowland streaked tenrec|
G. Cuvier, 1798
|Lowland streaked tenrec range|
Distribution and habitat
The species is found in tropical lowland rain forest, in the northern and eastern parts of Madagascar. They can be found on land, splashing in shallow waters or digging underground.
The lowland streaked tenrec (Hemicentetes semispinosus) belongs to the family Tenrecidae in the order Afrosoricida, and more specifically to the subfamily of the spiny tenrecs Tenrecinae. The average body size for H. semispinosus is a length of 140 mm (5.5 in) however adults have been recorded to grow up to a maximum of 172 mm (6.8 in). Body weight for adults of this species can range from 125–280 g (4.4–9.9 oz). This species has a black spiny pelage with yellow or chestnut-brown stripes that run the length of the body. There is a median yellow stripe that runs down the rostrum along with one dorsal and two lateral stripes that mark the length of the body and may serve as a warning to predators. Quills are present in this species being longer and more numerous on the head and nuchal area. However, the ventral region contains few to no quills but have the ability to detach in predation defense.
H. semispinosus possesses sensory hairs that are scattered on the dorsum that are similar to vibrissae. The streaked tenrec has an evolutionary adaptation for its semifossorial habits with a well developed lateral and long heads of M. triceps brachii and enlarged M. teres major that function as an extensor of the elbow joint and as an adductor of the upper arm for digging. This species also has elongated hands and second, third, and fourth digit adaptation that acts as the main fossorial adaptation. The middle of the skull of this species is long and low, the alveolar processes of the maxilla, premaxilla and mandible are reduced and the palate narrow. The teeth are small, spaced, and placed farther forward on the skull. The temporal muscles, sagittal, and nuchal crests are weaker compared to other tenrec species.
The lowland streaked tenrec is active both during the day and at night. Its diet is made up primarily of earthworms, but they will sometimes prey on other invertebrates as well. They may be seen stamping their feet on the ground with their fore-paws, an adaptation which is believed to increase earthworm activity for easier foraging. Most tenrecs possess a long snout for poking around in the ground to find their food. They are also capable of eating fruit.
Breeding takes place during October to December and possibly at other times, depending upon local food supply and temperature. The gestation period lasts 58 days, and the female gives birth to usually between 5 and 8 young. The young are weaned at 18 to 25 days.
The streaked tenrec lives in long, shallow burrows which are usually occupied by family groups.
Spines as tools
H. semispinosus has hard keratinous quills located in the mid-dorsal region that act as a sounding device and is thought to be used for communication between mother and young and/or a warning signal to predators. Movement of these quills causes the tips to rub together and create a high frequency sound. These quills are located in a small area of the mid-dorsal region in a group of seven to sixteen arranged in three rows. Five quills run laterally on each side and is flanked by five to six quills being light brown in color. The arrangement and number of quills does not alter during growth and neither does the length. The circumference of the quills however, does change from juvenile to adult.
When an individual is aggravated a defense response is produced by erecting its quills laterally and forward and produces sound when the quills vibrate. H. semispinosus has a highly developed sense of smell and this response along with foot stamping is also produced when the odor of a predator is detected. This display additionally occurs when males fight for females and when unfamiliar males come across one another. Female encounters however, have tactile contact and then increase the distance between each other.
The streaked tenrec has the ability to enter torpor seasonally however, it is dependent on altitude, age, fat stores, and temperature. Torpor for this species generally occurs during June and July and during winter. However, H. semispinosus is a facultative hibernator and will come out of torpor during winter and forage. When foraging the soil and leaf litter is prodded with the tip of the nose until prey is detected. Elongated hands and digit adaptation (digits 2, 3, and 4) are the tenrecs main digging apparatus allowing it to unearth and pull its prey form the earth.
The skull has an elongated rostrum with a slender jaw with small spaced dentition placed more forward in the mouth. This species has zalambdodont molars with a dental formula of I 3/3, C 1/1, P 3/3, M 3/3 having a total of 40 teeth. The sagittal crest and nuchal are less prominent in this species and the zygomatic processes are long and slender resulting in less projection from the sides of the skull. The occipital region in this species along with the visceral skeleton are commonly very conservative.
- Afrotheria Specialist Group (Tenrec Section); Jenkins, P. & Goodman, S. (2008). "Hemicentetes semispinosus". IUCN Red List of Threatened Species. Version 2008. International Union for Conservation of Nature. Retrieved 29 December 2008.
- Endo, H., Oishi, M., Yonezawa, T., Rakotondraparany, F., & Hasegawa, M. (2007). The semifossorial function of the forelimb in the common rice tenrec (Oryzorictes hova) and the streaked tenrec (Hemicentetes hemispinosus). Anatomia, histologia, embryologia, 36(6), 413-418.
- Marshall, C., & Eisenberg, J. (1996). Hemicentetes semispinosus. Mammalian Species, (541), 1-4. doi:10.2307/3504327
- Butler, P. (1941). A Comparison of the Skulls and Teeth of the Two Species of Hemicentetes. Journal of Mammalogy, 22(1), 65-81. doi:10.2307/1374685
- "Hemicentetes semispinosus (streaked tenrec)". Animal Diversity Web. Retrieved 2017-06-18.
- Endo, H., Koyabu, D., Kimura, J., Rakotondraparany, F., Matsui, A., Yonezawa, T., ... & Hasegawa, M. (2010). A quill vibrating mechanism for a sounding apparatus in the streaked tenrec (Hemicentetes semispinosus). Zoological science, 27, 427-432.
- Schunke, A. C., & Zeller, U. (2010). Chondrocranium and dermal bones of the lowland streaked tenrec Hemicentetes semispinosus (Afrosoricida, Tenrecidae) and their comparison with Potamogale and other insectivoran-grade placental mammals. Vertebrate Zoology, 60(1), 37-72.
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