The snake, which is not poisonous, sank its fangs into 12-year-old Robert Hartley when he visited Colchester's Natural History Museum on Monday.

The youngster even had to allow the creature to finish biting him - because removing the snake's mouth would have made the injury worse.

However, the incident has not put Robert off his interest in reptiles and he plans to return to the museum later in the week to visit the snake again.

Boa facts

The boa constrictor is a non-poisonous tropical snake It is found in Central and South America and often reaches lengths of up to 1.5 metres It belongs to the same family as the python and anaconda It can live for up to 30 years Boas seize their prey in their jaws, then entwine it in their powerful body coils and kill it by suffocation. Their prey is mainly of birds and small mammals The boa is nominally protected by the Convention on International Trade in Endangered Species (CITES)

"I like reptiles and I like the way snakes feel. That snake is very rare so it was a rare opportunity to go and touch it.

"It didn't hurt. It's just like someone pinching you a bit," Robert said.

Museum spokeswoman Marie Taylor said there would be an investigation into the incident.

She said: "Obviously we are concerned, but it was not hugely serious. We plan these events with health and safety in mind and we are very responsible.

"We had experts there and plenty of staff.

"Robert was a very enthusiastic - and he still is. It was dealt with professionally and he spent another good hour in the museum after being bitten."

Robert's mother Sylvia, from Great Bentley, Essex, said she thought the baby snake was tired.

She said: "Unfortunately, Robert was holding it when it lashed out.

"I think it was very tired and had been held by a lot of people."

Another child came out to tell Mrs Hartley that her son had been bitten by the boa.

The schoolboy had been holding the snake when it sank four fangs into his arm.