Evolution Of The Tube-Lipped Nectar Thron
Anoura fistulata, otherwise known as the tube-lipped nectar bat, is a nectarivorous species endemic to South America (Mantilla-Meluk et al. 2009). A. fistulata specializes in feeding on the nectar and pollen from larger flowering plants, but also frequently hunts insects to round out it’s diet (Muchhala et al. 2005). However, unlike other species of the same genus A. fistulata has co-evolved as a pollinator of the bellflower Centropogon nigricans (Muchhala et al. 2009). C. nigricans has developed a nectar-bearing corolla that is approximately 8 cm long–around 4 cm longer than most pollinating bat species can reach–and a downward facing stamen tube hanging above the entrance (Muchhala et al. 2005). C. nigricans flowers only open for approximately
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2005). The tongue is long and thin, with hair-like papillae a few millimeters in length at the tip to aid in nectar retrieval (Muchhala et al. 2005). While extremely long tongues are a common adaptation for feeding in many insects, it is rarely seen in mammals, and in bats it is unique to A. fistulata (Muchhala 2006). In fact, the chameleon is the only vertebrate with a longer tongue relative to body size (Muchhala 2006). Muchhala et al. reasoned that this is because tongue length is directly correlated to the length of the jaw and mouth parts, which are not usually widely variable in mammals. However, A. fistulata has evolved a distinctive glossal tube, which allows the tongue to be stored inside the rib cage instead of in the jaw. By having the tongue attach below the breastbone instead of in the oral cavity, A. fistulata has been able to evolve a long tongue to feed on nectar located in the long corollas of C. nigricans that other bats cannot reach (Muchhala 2006).
In addition to a unique tongue structural system, Muchhala et al. also describes A. fistulata as having developed a peculiar lip. The lower lip protrudes forward about 4 millimeters past the upper lip, and the edges of the lower lip roll inward towards each other, effectively creating a sheath-looking
2005). The tongue is long and thin, with hair-like papillae a few millimeters in length at the tip to aid in nectar retrieval (Muchhala et al. 2005). While extremely long tongues are a common adaptation for feeding in many insects, it is rarely seen in mammals, and in bats it is unique to A. fistulata (Muchhala 2006). In fact, the chameleon is the only vertebrate with a longer tongue relative to body size (Muchhala 2006). Muchhala et al. reasoned that this is because tongue length is directly correlated to the length of the jaw and mouth parts, which are not usually widely variable in mammals. However, A. fistulata has evolved a distinctive glossal tube, which allows the tongue to be stored inside the rib cage instead of in the jaw. By having the tongue attach below the breastbone instead of in the oral cavity, A. fistulata has been able to evolve a long tongue to feed on nectar located in the long corollas of C. nigricans that other bats cannot reach (Muchhala 2006).
In addition to a unique tongue structural system, Muchhala et al. also describes A. fistulata as having developed a peculiar lip. The lower lip protrudes forward about 4 millimeters past the upper lip, and the edges of the lower lip roll inward towards each other, effectively creating a sheath-looking