TANZANIA WORLD WONDERS Kihansi spray toad
From Wikipedia, the free encyclopedia
The
Kihansi spray toad,
Nectophrynoides asperginis, is a small toad
endemic to Tanzania.
[2][3] The species is live-bearing and insectivorous.
[2] The Kihansi spray toad is currently categorized as "Extinct in the wild" by the
International Union for Conservation of Nature (IUCN), though the species persists in
ex situ, captive breeding populations.
Physiology
The Kihansi spray toad is a small, sexually dimorphic anuran, with
females reaching up to 2.9 cm (1.1 in) long and males up to 1.9 cm
(0.75 in).
[2] The toads display yellow skin coloration with brownish dorsolateral striping.
[4] Females are often duller in coloration, and males normally have more significant markings
[5] Additionally, males exhibit dark inguinal patches on their sides where their hind legs meet their abdomens.
[5] Abdominal skin is translucent, and developing offspring can often be seen in the bellies of gravid females.
[5]
These toads have webbed toes on their hind legs,
[5][4] but lack expanded toe tips.
[4] They lack external ears, but do possess normal anuran inner ear features, with the exception of
tympanic membranes and air-filled middle ear cavities.
[6]
Habitat
Prior to its extirpation, the Kihansi spray toad was endemic only to a
two hectare area at the base of the Kihansi River waterfall in the
Udzungwa escarpment of the
Eastern Arc Mountains in Tanzania.
[7] The Kihansi Gorge is about 4 km long with a north-south orientation.
[4] A number of wetlands made up the habitat of this species, all fed by spray from the Kihansi River waterfall.
[4] These wetlands were characterized by dense, grassy vegetation including
Panicum grasses,
Salaginalla kraussiana moss, and snail ferns (
Tectaria gemmifera).
[4] Areas within the spray zones of the waterfall experienced near-constant temperatures and 100% humidity.
[4]
Extinction in the wild
The
extinction in the wild of the Kihansi spray toad was mainly due to habitat loss following the construction of
Kihansi Dam in 1999, which reduced the amount of water coming down from the waterfall into the gorge by 90 percent.
[1] This led to the spray toad's
microhabitat
being compromised, as it reduced the amount of water spray, which the
toads were reliant on. A sprinkler system that mimicked the natural
water spray was not yet operational when the Kihansi Dam opened.
[1]
In 2003 there was a final population crash in the species. This
coincided with a breakdown of the sprinkler system during the dry
season, the appearance of the disease
chytridiomycosis, and the brief opening of the Kihansi Dam to flush out sediments, which contained
pesticides.
[1] The last confirmed record of wild Kihansi spray toads was in 2004.
[1]
Survival in captivity
The
Bronx Zoo
initiated a project where almost 500 Kihansi spray toads were taken
from their native gorge in 2001 and placed in six U.S. zoos as a
possible hedge against extinction.
[8][9][10] Initially its unusual life style and reproduction mode caused problems in captivity, and only Bronx Zoo and
Toledo Zoo were able to maintain populations.
[9]
By December 2004, less than 70 remained in captivity, but when their
exact requirements were discovered greater survival and breeding success
was achieved.
[8][9]
In November 2005, the Toledo Zoo opened an exhibit for the Kihansi
spray toad, and for some time this was the only place in the world where
it was on display to the public.
[8] The Toledo Zoo now has several thousand Kihansi spray toads,
[8][11] the majority off-exhibit. The Bronx Zoo also has several thousand Kihansi spray toads,
[11] and it opened a small exhibit for some of these in February 2010.
[9][12] In 2010 Toledo Zoo transferred 350 toads to
Chattanooga Zoo,
[8] which has created a small exhibit for them. Groups numbering in the hundreds are now also maintained at
Detroit Zoo and
Omaha's Henry Doorly Zoo.
[1
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