# Mertens' Water Monitor (*Varanus mertensi*) Mertens' Water Monitor is a big lizard that loves to swim! It has a long tail and can be found near water. These lizards are great at catching fish and other tasty treats in the water. - **Category:** [Reptiles](https://www.snappit.app/explore/categories/reptile) - **Rarity:** Common - **Danger:** 2/5 · Low - **Habitat:** Wetlands - **Also known as:** Mertens' Monitor ![Mertens' Water Monitor](https://commons.wikimedia.org/w/index.php?title=Special:Redirect/file/Varanus_mertensi.jpg&width=800) Photo: Phasmatisnox at English Wikipedia, CC BY 3.0 · [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Varanus_mertensi.jpg) ## Appearance The Mertens' Water Monitor has a dark grey to blackish-brown body with numerous yellow or cream spots that often form ocelli. Its underside is pale yellow. It features a distinctive flattened snout with nostrils positioned on top, aiding its aquatic lifestyle. ## Taxonomy - **Kingdom:** Animalia - **Phylum:** Chordata - **Class:** Squamata - **Order:** Lacertilia - **Family:** Varanidae - **Genus:** Varanus ## Interesting facts - Baby monitors have much brighter patterns than adults, helping them blend into their surroundings! - These lizards can walk along the bottom of rivers and lakes, exploring silently! - They spend most of their entire lives splashing, hunting, and relaxing in freshwater! - They use their forked tongue to 'smell' chemicals in water, finding hidden snacks! ## Special abilities - **Underwater Vision:** Mertens' Water Monitor has clear vision both in air and water, allowing them to spot prey above and below the surface. - **Streamlined Swimmer:** Mertens' Water Monitor can powerfully propel itself with a strong, laterally flattened tail that helps them chase fish. - **Submerged Snorkel:** Mertens' Water Monitor can breathe with just its nostrils above water because they are placed high on its flattened snout. ## Measurements & details - **Length:** 80-130 cm - **Weight:** 2-5 kg - **Lifespan:** 10-15 years - **Speed:** 15 km/h - **Swim Speed:** 15 km/h - **Clutch Size:** 6-18 - **Incubation:** 190-210 days - **Maximum Depth:** 10 m ## Diet & Feeding A speedy swimmer that eats fish, frogs, and other small aquatic creatures in northern Australia's waterways. - **Age differences:** Juveniles mostly eat insects and very small aquatic prey, while adults consume larger fish and frogs. - **Primary Foods:** Fish, Frogs, Crayfish, Water insects, Small reptiles - **Foraging Method:** Pursuit ## Ecological connections - **Eats:** Green Tree Frog (*Litoria caerulea*) — A common frog species preyed upon. - **Eats:** Eastern Rainbowfish (*Melanotaenia splendida*) — A widespread fish often hunted. - **Eaten by:** [Saltwater Crocodile](https://www.snappit.app/explore/saltwater-crocodile) (*Crocodylus porosus*) — Larger crocodiles can prey on monitors. ## Traits - [Webbed Feet](https://www.snappit.app/explore/traits/webbed-feet): Characterized by having toes connected by a membrane, typically aiding in swimming. - [Solitary](https://www.snappit.app/explore/traits/solitary): Solitary animals live alone for most of their lives, only interacting with others for mating or parental care. - [Piscivorous](https://www.snappit.app/explore/traits/piscivorous): Piscivorous organisms are animals that primarily subsist on a diet of fish. - [Ambush Predator](https://www.snappit.app/explore/traits/ambush-predator): An ambush predator hunts by patiently waiting and concealing itself, then launching a sudden attack when unsuspecting prey comes within range. - [Wetland](https://www.snappit.app/explore/traits/wetland): This habitat trait identifies species found in wetlands, which are areas of land saturated with water, either permanently or seasonally, including marshes, swamps, and bogs. - [Carnivorous](https://www.snappit.app/explore/traits/carnivorous): This trait identifies organisms whose diet consists entirely or primarily of animal tissue. - [Diurnal](https://www.snappit.app/explore/traits/diurnal): Diurnal animals are primarily active during daylight hours, typically resting or sleeping at night. - [Giant](https://www.snappit.app/explore/traits/giant): Giant describes organisms or objects of significantly larger size than average for their species or type. ## Collections - [Reptiles](https://www.snappit.app/explore/collections/reptiles) ## Safety **Danger:** 2/5 · Low Always watch from a distance and never try to touch wild lizards. ## Frequently Asked Questions ### How to identify Mertens' Water Monitor? Compare toes, scales, head shape, crests and tail proportions. Many lizards can drop and regrow their tails, so a short tail isn't always a species trait. Lizard Identifier: upload a photo and compare the visible details. ### How long is Mertens' Water Monitor? 80-130 cm ### How much does Mertens' Water Monitor weigh? 2-5 kg ### How long does Mertens' Water Monitor live? 10-15 years ### How fast can Mertens' Water Monitor move? 15 km/h ### What does Mertens' Water Monitor eat? A speedy swimmer that eats fish, frogs, and other small aquatic creatures in northern Australia's waterways. ### How fast can Mertens' Water Monitor swim? 15 km/h ### Where is Mertens' Water Monitor usually found? Wetlands ## More Reptiles - [Pond Slider](https://www.snappit.app/explore/pond-slider) (*Trachemys scripta*) - [Western Fence Lizard](https://www.snappit.app/explore/western-fence-lizard) (*Sceloporus occidentalis*) - [Common Five-lined Skink](https://www.snappit.app/explore/common-five-lined-skink) (*Plestiodon fasciatus*) - [Desert Spiny Lizard](https://www.snappit.app/explore/desert-spiny-lizard) (*Sceloporus magister*) --- Source: [Mertens' Water Monitor: Facts & Places to See — Snappit](https://www.snappit.app/explore/mertens-water-monitor)