Zoo-pedia > Crocodile Lizards - General observations

Crocodile Lizards - General observations

by Kevin Stevens. Article first published in the International Herpetological Journal 2006.

Some general observations on the Crocodile Lizard (Shinisaurus crocodilurus)

Introduction

During the early 1990’s I took my first trip to the Dutch snake day that was then held at the university in Utrecht. I often travelled with fellow herpers Bryan Ballantyne and Malcolm Curruthers, and we always tried to visit Rotterdam (Blijdorp) Zoo in the same trip. Even though we were all confirmed snake keepers I always remembered being most impressed with one reptile in the zoo’s collection, the Crocodile lizard. I guess I was a little obsessive about this little fellow taking many photographs and promising myself that I would one day keep them myself. Fast forward to Terraristaka, Hamm, Germany in March 2003, and Melanie spots one for sale – knowing them well from my enthusiastic story about the one at Rotterdam zoo. Without a thought he was ours and came home with us to the UK. This is the start of story, to date of mine and Mel’s love affair with these little lizards.

Background information

First described by Ahl in 1930, it is the only member of the family Shinisauridae and it is thought to be closely related to the lizards of the genus Xenosaurus in southern Mexico and Guatemala. The species is regarded as very rare, with figures as low as 2000 wild individuals left, Zhang estimated 2,500 in 1991. It is listed as CITES annex II. They occur in Southern China in low volumes, around scattered ranges near the 24' Northern Latitude and 111' Eastern Length Parallel. In that area there were 4 small ranges known in 1985 and 3 in 1991. The ranges are often as small as a few dozen square kilometers. Dayao Shan mountain range of east-central Guangxi Province and the Kwangsei province, both in China, have been listed as having had small populations. They are usually found around 200-700 metres above sea level. When found in the wild, they are usually solitary and found in and around streams and pools. They are said to bask on logs overhanging water and that they leap into the water when threatened. They can use their tails to swim powerfully and can stay underwater for up to 30 minutes. I have heard that they are widely used in Chinese medicine, despite their rarity.

Natural climate patterns are pretty much constant throughout their range, helped by the fact that where they occur is of a similar (highish) altitude. Temperatures in China varies from around –2C in the winter to an absolute maximum of 35C in the summer – although these high temperatures are unlikely where Shinisaurus occur. High rainfall occurs in April and May. All in all, similar weather pattern to our own here in the UK.

They are one of the most stunning small lizards I have come across. Growing to around 40cm long they have a perfect replica of a crocodilian tail, the back also has a similar resemblance - and then someone has seen fit to stick a totally non-crocodile head on! The head more closely resembles an Agamid species of lizard, perhaps with a lsightly “startled” expression! Colours vary from browns, reds, greens, and grey, writers often quote that males have red throats and bellies were as females have white bellies and throats. Speaking to most of the breeders I know they say that colouration plays little part in sex determination.

They are known to hibernate for three to four months, mating occurs during the warmest Chinese month, August. Live young are born between April and May, figures often quoted are around 2-9 are born – but I have heard of reports of litters as large as 20. They are around 15cm long at birth

The story continued

Our first Crocodile lizard was a little cutie, about half grown. Mel has a different approach to my own when identifying animals and he was to be known as Gomek – after the huge American Alligator she had seen at St. Augustine Alligator Farm in Florida. We housed him in a vivarium measuring 100cm (width) x 45cm x 45 cm, heated with a ceramic heater suspended at one end. Temperatures were governed by a Habistat Pulse proportional thermostat to 26C (occasionally 28C) day time, dropping to around 18-20C at night. Lighting is only provided by a Zoo-med Reptisun 5.0, we have made no other light provision. Floor covering was damp sphagnum moss with a cat litter tray for water – we had been told that they can drown in deep water, despite being strong swimmers. Various pieces of cork bark were used for hiding places and we also provided artificial plants and branches for climbing. Diet initially was mainly fast moving insects such as crickets, with the inclusion of slow moving waxworms, earthworms etc – until we realised that he was not quick enough to catch the fast movers. Earthworms seem to be a firm favourite. All food is gut loaded using a commercially available product called Bug grub. Nutrobal and Calypso cricket dust is mixed in equal amounts and dusted onto the food. Whilst young we feed everyday, but only dust the food five days out of seven. As adults we will change this to our typical adult lizard regime of feeding just about daily but powdering the food only three times a week.

In March 2004 we managed to secure another specimen at Terraristaka, a little smaller than Gomek so he was kept separately in the same manner as previously described. He was identified as Schnitzel, I think Mel was a little obsessed by the German food on her travels around Germany! Later that year Gomek, after doing very well and growing well suddenly died showing no signs of illness at all. We added to our group in 2005, again by visiting Terraristika, by purchasing another two young adults and also two babies. The adults were purchased from a Scandinavian breeder who kept them outdoors – all year! This was probably the main reason for them being green coloured – this eventually disappeared, it was algae staining! These adults are about the same size of Schnitzel and were named Rosti and Gomek (II). The babies were, and still have not been given identifying names. We have kept the three young adults together, and the two youngsters are together in another vivarium

We are planning a new method of keeping our Shinisaurus based along the more naturalistic vivaria often seen on the continent. We intend to heavily plant them with real plants and mosses with larger water areas and slow moving water falls. Our findings will be published in the future.

Some early observations

When keeping this species the first thing that strikes you is their behaviour. They do not behave like most lizards. They have not shown a big tendency to bask, they are very secretive and remain hidden for long periods of time. They are not overtly active, are slow moving and are easily picked up. Occasionally they are seen perched on a branch over hanging their water. This is becoming more frequent as they get older –perhaps the hiding tendencies are more in keeping with their young ages and natures’ way of getting babies to survive. One strange behaviour not changed as they age is their “motion freezing” when handled. Once they are picked up they do not move a muscle! Not quite feigning death, but certainly to the point that makes you worry that you have poorly animals when you first start keeping them!

References

Most of the information I could find was taken from the internet, and thus references can not be listed in the traditional way. Here is a list of pages that I found useful for keeping this species and where I also dragged information from for this article.

http://www.agamainternational.com/pages/shinisaurus.html

http://www.shinisaurus.de

http://srs.embl-heidelberg.de:8000/srs5bin/cgi-bin/wgetz?-e+%5BREPTILIA-Species:'Shinisaurus_SP_crocodilurus'%5D

http://www.reptilia.dk/Krybdyr_vi_holder_nu/Oegler/Shinisaurus_crocodilurus/shinisaurus.htm