6869. Identify monitor lizard photo

 

This photograph appears to show a Malayan Water Monitor (Varanus salvator), rather than a Clouded Monitor (Varanus nebulosus).

Why I identify it as a Malayan Water Monitor

• Aquatic behaviour: The lizard is swimming with only its head and back above the water. Varanus salvator is highly aquatic and is an excellent swimmer.
• Long, streamlined body: The visible body and neck are consistent with the elongated form of a Water Monitor.
• Head and snout: The head appears relatively long and robust, with the nostril positioned very close to the tip of the snout—an important distinction from the Clouded Monitor.
• Environment: It appears to be in a waterway surrounded by overhanging vegetation, which is typical Water Monitor habitat in Singapore.
• Colour: The dark, almost black appearance in this photograph can occur in V. salvator, particularly under subdued lighting and when the animal is wet.

Identification: Malayan Water Monitor — Varanus salvator.

One interesting feature of your photograph is that the lizard is almost completely submerged. That makes it a particularly good illustration for a Singapore wildlife video: “Why is the Malayan Water Monitor such a good swimmer?” Its long, laterally compressed tail provides powerful propulsion, while its body and limbs are adapted for swimming.

If you're using this for your Seletar Simpang Kiri River wildlife photography, I would caption it:

Malayan Water Monitor (Varanus salvator) swimming quietly through the waters of Singapore.

The photograph provides enough evidence for a probable identification, although the nostril is partly obscured by the angle and water, so I would not call it absolutely diagnostic from this single image.

 

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The main difference between the Malayan water monitor and the clouded monitor lies in the position of their nostrils, their size, and their preferred habitats. [1]

Key Differences at a Glance

Nostril Position:
• Malayan Water Monitor: Nostrils are located right at the tip of the snout, acting like a built-in snorkel.
• Clouded Monitor: Nostrils are positioned midway between the eyes and the tip of the snout. [1, 2]
Size:
• Malayan Water Monitor: Much larger, growing up to 2 to 3 meters (6.5 to 10 feet) long.
• Clouded Monitor: Smaller, generally reaching a maximum length of about 1.5 meters (5 feet). [1, 2, 3, 4]
Tail Shape:
• Malayan Water Monitor: Has a flattened, vertically compressed tail designed to help it swim efficiently.
• Clouded Monitor: Features a rounder, more slender tail. [1, 2, 3, 4]
Habitat:
• Malayan Water Monitor: Semi-aquatic; frequently seen near canals, reservoirs, ponds, mangroves, and urban waterways.
• Clouded Monitor: Terrestrial and arboreal; prefers forests, scrublands, and wooded parks where it climbs trees and searches through leaf litter. [1, 2, 3, 4, 5]
Diet:
• Malayan Water Monitor: Carnivorous and opportunistic scavengers eating fish, small mammals, birds, and reptiles.
• Clouded Monitor: Specializes more in terrestrial invertebrates like insects (beetles, grasshoppers) and small vertebrates