Friday, 23 January 2015

Holy Cross Frog

Yellow Holy Cross Frog (Notaden bennettii)
Holy Cross Frog
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Myobatrachidae
Subfamily: Limnodynastinae
Genus: Notaden
Species: Notaden bennettii
Conservation Status: Least Concern (Not Threatened)
Common Name (s): Crucifix Toad or Holy Cross Frog

The Crucifix Toad is an Australian, odd-looking fossorial frog and one of the few Australian frogs to exhibit aposematism. As you can see on the pictures, it is named after the cross on its back.
 
Distribution and Habitat
The holy cross frog occurs in central inland New South Wales and the interior of southern Queensland, west of the Great Dividing Range. The species occupies an area of approximately 615,000km2. The species is ground-dwelling and prefers arid areas.


Map showing the range and distribution of the crucifix toad
Distribution of the Crucifix Toad

Description
It is a small and very round frog. The nose is blunt, and the legs and feet are small. Adult males reach a length of up to 6.3 centimetres (2.5 in) whereas females a length of 6.8 centimetres (2.7 in). The feet have little "spades" to help them burrow deeply.

N. bennettii is probably the most distinctive species within the Notaden genus. Whereas most Notaden frogs are dark brown in colour, this frog exhibits many bright colours, along with the "trademarked" cross centered on the back.

The cross is outlined with large, black dots, and filled with white, black and red dots. The ventral surface is white, and the flank's blue.

A dark brown male crucifix toad
Male crucifix toad

Diet
The frog's diet primarily consists of ants and termites.

Behavior and Reproduction
The crucifix frog spends most of its life underground and only emerges after heavy rains. Upon heavy rain, the frogs emerge from the ground, and begin breeding in temporary ponds. The males call from within the pond to attract the female. This call is a "woop". After mating, the eggs are deposited in the pond.

Tadpoles develop rapidly, to take advantage of the wet conditions and to reduce the risk of them dying from the pond drying up. The cycle is so quick that it can take as little as 5-6 weeks.

To survive long periods without water, the holy cross frog will bury itself underground and encase itself in a cocoon.

Holy cross frog compared to a 20 cent australian coin
Holy Cross Frog with Australian 20c coin for comparison

Frog Glue
Interestingly, the species exudes a tacky and elastic glue-like substance onto its dorsal skin when provoked. The purpose of this glue is uncertain. It may be intended to confuse and deter predators such as snakes, or to trap biting insects, which would later be consumed when the frog sheds and eats its skin.

Males have been recorded to use this glue to attach themselves onto the larger females during mating. The glue has been found to be stronger than the currently available non-toxic medical adhesives and is being researched for possible applications. It is a protein-based pressure-sensitive adhesive that functions even under wet conditions.


This video shows one of four captive Crucifix Frogs kept at the Australian Museum.


Conservation Status
The species is currently listed by the IUCN as Least Concern due to its wide distribution and seemingly large population. Populations appear to have a stable trend

Habitat loss/degradation due to farming related activities is a threat to the species in parts of its range. Competition from the tadpoles of Bufo marinus can effect the growth of the tadpoles.


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