Hooded scaly-foot
| Pygopus nigriceps | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Order: | Squamata |
| Family: | Pygopodidae |
| Genus: | Pygopus |
| Species: | P. nigriceps |
| Binomial name | |
| Pygopus nigriceps Fischer, 1882 | |
 | |
The hooded scaly-foot, Pygopus nigriceps, is an endemic Australian legless lizard of the family Pygopodidae.[1]
Description
Adult hooded scaly-foots range from 45 to 55 cm long,[2][3] with an average snout to vent length of 22.7 cm.[4] Females are generally larger than males.[1] Hooded scaly-foots show no trace of forelimbs, whilst the hind limbs are reduced to scaly flaps.[1][2][5] These hind limbs are small and paddle-shaped, with modified scales which do not aid in movement.[2][3]
The scales of the hooded scaly-foot are smooth and weakly glossed.[2][3][6] Usually, it has 120 or more ventral scales,[4][6] which are in a paired series, much larger than the adjacent body scales.[4][5] Body colour varies from brown to reddish-brown,[4] with desert specimens usually a more orangish colour and other individuals a duller brown.[2] It is white below.[3][5] The species has little to no body pattern, with oblique dark lines converging mid-dorsally.[4][6]
These scaly-foots are characterised by black bands across the head and neck which may look like a hood.[4][5][6] This hood comprises a band across the eyes onto the lips, a dark smudge on the nostrils, and a broad band across the neck.[3][4][6] These dark bands may fade or merge with age.[3][5] The lidless eye is well developed,[2][5] covered with a transparent spectacle.[1][6] The species is able to lick clean this spectacle using its broad, fleshy tongue.[3] It also retains conspicuous ear openings.[1][3]
The hooded scaly-foot can be differentiated from the four other species in the genus Pygopus if the nostril contacts the first upper labial scale.[4][6]
Taxonomy
The closest relatives of the pygopodids are the Gekkonidae.[1][4][5] The pygopodids and geckos share a number of characteristics; the two families may actually be one, and pygopodids may actually be limbless geckos.[4] Shared characteristics include: the production of parchment-shelled eggs in clutch sizes of two;[1][4] the ability to lick clean the clear spectacles which cover their lidless eyes;[6] and the sharing of a voice in the form of a “harsh squeak”.[4] The skulls and inner ears of the pygopodids are also similar to those of geckos.[5]
Ecology
The hooded scaly-foot is found throughout Australia, except for the wetter areas of the south and Tasmania.[2][5] The family Pygopodidae is endemic to Australia and New Guinea.[5]
The species is mostly nocturnal, due to the generally hot weather where it occurs, although in cooler conditions, it forages by day.[2][3] It is a terrestrial surface-dweller, but individuals have been noted up to 1.5 m above the ground in vegetation.[5] Captive scaly-foots have lived up to seven years, but little is known about ages of individuals in the wild.[5]
Hooded scaly-foots are found in a range of habitats,[2][3] favouring dry open habits.[4] They are found particularly in sandy deserts vegetated with triodia,[4][5] but also in open woodlands and shrublands.[3] The species shelters under rocks and woody debris, in grass tussocks and soil cracks, abandoned burrows, insect holes, and in termite mounds.[3][4][6]
Diet
The hooded scaly-foot feeds predominantly on surface-active arthropods.[1][4][6] Insects are the main prey type, while it is also noted to feed on spider egg sacks and scorpions.[1][3][4][5] The species has been observed to actively search for prey.[5] Once caught, larger prey is crushed and disabled as the hooded scaly-foot rotates its body rapidly, in a crocodile-roll fashion.[3][5] Body fluids are then licked up.[3]
Behavior and defense
Scaly-foots move through lateral undulations of their bodies and tails,[5] and in open terrain they have been noted to move in wriggling leaps.[6] The hind-limb flaps are held alongside the body during movement, although they may be extended when stressed or when climbing.[5] As stated earlier, hooded scaly-foots have a voice. This harsh squeak is emitted under stress and occasionally in social interactions.[5]
When disturbed, hooded scaly-foot raise their heads and fore parts of their bodies from the ground, flatten their necks, and flicker their tongues, occasionally striking out.[3][4][5] The species does this in apparent mimicry of venomous snakes, to deter predators.[3][4][5] The markings on the hooded scaly-foot resemble those of young brown snakes.[4] When grasped, they struggle fiercely, rotating their bodies and uttering long squeaking sounds.[4] They readily shed their tails and will regenerate a new one.[2][6] The regenerating tail can be identified through a change in scale arrangement and pattern.[6]
Reproduction
Hooded scaly-foots are oviparous, laying two parchment-shelled eggs per clutch.[3][5] Pygopus species have been noted to lay communally,[1][5] while known incubation periods range from 66 to 77 days.[5] Pelvic spurs, modified spine-like scales, are found in addition to the hind-limb ‘flaps’ on males, are thought to assist the male in gripping the female.[2]
Predation
Predators of the hooded scaly-foot include: raptors, elapid snakes, goannas, feral cats, and foxes. Burton’s snake lizard (Lialis burtonis) is also known to eat legless lizards. In all cases, legless lizards are a minor component of the predator’s diet.[5]
Differentiating from snakes
Legless lizards are often killed due to their similar appearance to snakes.[4] A number of external characteristics can be used to distinguish legless lizards (including the hooded scaly-foot) from snakes:
- Flap-footed lizards have vestigial hindlimbs
- Legless lizards have broad, fleshy tongues, dissimilar from the forked tongues of snakes
- Most legless lizards have external ears
- Ventral scales are in a paired series
- Unbroken tails in legless lizards are much longer than the body, whereas snake bodies are longer than their tails.[2][4][6]
References
- 1 2 3 4 5 6 7 8 9 10 Patchell, Frederick; Richard Shine (February 1986). "Food Habits and Reproductive Biology of the Australian Legless Lizards (Pygopodidae)". Copeia. 1986 (1): 30–39. doi:10.2307/1444884. JSTOR 1444884.
- 1 2 3 4 5 6 7 8 9 10 11 12 Hoser, Raymond (1989). Australian Reptiles and Frogs. Pierson & Co. pp. 79–83.
- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Cronin, Leonard (2001). Australian Reptiles and Amphibians. Envirobook. p. 166.
- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Wilson, Steve (2003). A Complete Guide to Reptiles of Australia. New Holland: Reed. pp. 102–122.
- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Shea, Glenn. "Fauna of Australia: Family Pygopodidae" (PDF). Archived from the original (PDF) on 24 August 2012. Retrieved 16 June 2012.
- 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Wilson, Steve (2005). A Field Guide to Reptiles of Queensland. Australia: New Holland. pp. 62–69.