The RSPCA has criticised London Zoo after a rare Komodo dragon fell to her death while scaling a wall.
The Komodo dragon can live for 20 years
Six-feet-long Nina, who weighed 44lbs, died after scrambling up an eight foot dividing wall to reach her mate.
The Zoological Society of London (ZSL), which has launched an inquiry into the death, had hoped Nina and mate Raja would be a major attraction.
But an RSPCA spokesman told BBC London it was shocked that London Zoo was so ill-prepared.
A zoo spokesman said Nina's action was "both spontaneous and entirely out of character".
London Zoo's curator Dr David Field: "The design of the enclosure was thoroughly researched drawing on the knowledge of the world's leading reptile experts, but sadly this individual female dragon's agility far exceed our expectations and research.
"Immediate measures are being put in place to prevent a similar incident happening again and we are carrying out a thorough investigation into what occurred."
Bu an RSPCA spokesman said: "The full biological needs and abilities of any animals should be fully assessed before they are placed in a captive environment.
"From the information we have been provided with, it appears this was not done in the case of the Komodo dragons.
The zoo hoped Raja would mate with Nina
"We are frankly shocked that London Zoo was so ill-prepared - especially given the rarity of the species.
"Komodo dragons are large, strong animals that can be aggressive towards each other.
"From what we have been given by, it appears these well-known biological facts were not taken into account in the design of the captive-facilities at London Zoo."
Komodo dragons, which inhabit a small number of the Indonesian islands, are the largest lizards and can live for 20 years.
There are believed to be about 5,000 left in the wild.