Lowland streaked tenrec

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.[3] 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).[4] This species has a black spiny pelage with yellow or chestnut-brown stripes that run the length of the body.[4][3] 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.[4]

H. semispinosus possesses sensory hairs that are scattered on the dorsum that are similar to vibrissae.[4] 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.[3] 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.[5]

These tenrecs, H. semispinosus, are threatened primarily by the loss of their natural habitat due to continuous deforestation, as it is with many other animals in the Madagascar region. This species is also being hunted for food. [6]

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.[7] 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.

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.[4][8] Movement of these quills causes the tips to rub together and create a high frequency sound.[4] These quills are located in a small area of the mid-dorsal region in a group of seven to sixteen arranged in three rows.[4][8] 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.[8]

When an individual is aggravated a defense response is produced by erecting its quills laterally and forward and produces sound when the quills vibrate.[4][3] 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.[4][9] 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.[4] It uses its quills to communicate in two different ways, by raising them in agitation or by rubbing them together in a method known as stridulation – best known as the type noise produced by crickets and cicadas. The sound produced is too high to be perceived by human ears. [9]

The streaked tenrec is the only mammal known to use stridulation for generating sound, a method more commonly associated with insects and snakes.[10][11] Due to its rarity, there are not sufficient information regarding the functional-morphological mechanism of the streaked tenrec. The sounding quills are different from the spines and hair and are found in the mid-dorsal region of the streaked tenrec. The arrangement and length are similar throughout the streaked tenrec's life span, making up three rows in its midline area and adjacent areas bilaterally.[12] Cutaneous muscles underneath the quills were confirmed and are known as quill vibrator disc; they are around 16.8 mm long and 8.55 mm in width for an adult. These cutaneous muscles were the apparatus that contribute the vibration of the quills and production of sound for communication. [13]