A look at the Family Agamidae

Hydrosaurus

Sailfin Lizards

Introduction

These magnificent lizards are the largest agamids and among the most impressive in appearance. From a keeper's point of view, however, they have some major disadvantages. Firstly, they require large enclosures, both long and tall, with branches to bask on and a container of water large enough to immerse themselves in. Secondly, their temperament is rather nervous, and they share with Water Dragons the alarming habit of sudden headlong flights into the side of a cage, particularly if the barrier is glass. Most are imported from the Philippines and often carry worms and the additional possibility of protozoans. Nor are they particularly sociable: deVosjoli recommends keeping them singly or in single pairs, despite the large cage.

All this makes Hydrosaurus really lizards for specialists, and certainly not for beginners. If however the disadvantages can be met with time and money, then they are by no means unkeepable and may be rewarding if persevered with.

In the wild Hydrosaurus are, like water dragons, green iguanas and basilisks, found in the immediate vicinity of water deep enough to dive into even during the dry season. Again, like these other agamids and iguanids, they often lay on a branch above the water, so that if they feel sufficiently threatened they can dive for safety. Manthey and Schuster note that the lizards are very faithful to one site.

The genus is characterised by a length of about 1 metre or more, of which two thirds is tail. The digits have lobelike edges of skin. The tail is laterally compressed and is used as a paddle when the lizard is swimming. The most significant feature is of course the crests which give the genus its common name: a frontal, nape and dorsal crest running down the vertebrae, and a further tail crest. Dorsal scales are keeled, and a typanum is visible. Femoral pores are present. The tail crest is taller in adult males than in adult females, but it is impossible to distinguish the sex of juveniles externally.

Hydrosaurus are omnivorous, the juveniles being mainly insectivorous but later consuming more vegetable matter in their diet. There does not seem to be exact agreement on the portion of vegetable versus animal matter consumed. For care requirements, see Manthey and Schuster and deVosjoli.

In the Philippines at least, Hydrosaurus is sometimes consumed by humans, and Alcala suggests that this is one species that could be farmed. DeVosjoli also suggests the establishment of some system of management for sustained use without endangering the species.

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