The Gappa are a race frozen in the arctic for thousands of years.
In appearance Gappa look like a cross between a bat and a Spider. They have thick wiry fur. They have eight legs set out like a spiders. They have the wrinkled nose of a Bat. The legs are long and bony with bristles coming off them. The front two legs have long fingers on the end, these are used to feel around in the dark. The Gappa have limited sight and require on echolocation to find their way around, they do this by making high-pitched squeaking noises. Gappa communicate using a telepathic field that can also be used to possess beings.
Having lived on an Ice planet Gappa have no tolerance to heat. High temperatures kill them in seconds. Gappa only have a weak exoskeleton and so can easily be killed by crushing or throwing them.
The Gappa life cycle was a normal reproductive one but due to mass numbers being wiped out the Gappa began laying eggs in victims bodies where the Gappa grows up before hatching.
Gappa are a primitive race with no technology. They merely eat and reproduce in order to survive and have little intelligence.
The Gappa originated on Hydropellica but they ate so much all other species became extinct and slowly the Gappa began to die out. A group of Modrakanians took the last Gappa from the planet intending to take it home and preserve it so the Gappa would not become extinct but the ship crashed on Earth. The Modrakanians were killed in the crash but the Gappa escaped. They had crashed during the Stone Age. The Gappa was driven by cavemen, using their new invention fire, down into the ice where it was frozen. In the 2090s the governments began moving sheets of ice into Snowglobe's and the Section of ice containing the Gappa was moved to Snowglobe 7.
The Gappa awoke and used two Humans and a Flisk as hosts to breed a new group of Gappa. The skulls of the hosts were found by workers from Snowglobe 6 who believed they were eggs, the eggs were taken to the hospital at Snowlgobe 6. The "eggs" began to disintegrate and when the dust was breathed in the being became unconscious. Soon many of the hospital staff had breathed in the dust. The infected people breathing it out into others also spread the dust. When Maxwell O'Keefe and his assistant Curtis Rabley arrived at Snowglobe 7 the Gappa attacked them capturing Maxwell and using him as a host, Rabley escaped killing a Gappa with bullet fire as he went. The Gappa used their telepathic link to awaken the infected people at the hospital and commanded them to come to Snowglobe 7 and hand themselves over to be eaten.
The Doctor and Twelve arrived at the Gappa's lair and this distracted them resulting in the telepathic link being broken. The Gappa pursued them but were defeated but guards using flamethrowers. The Gappa retained a telepathic link with Beth Cowley and made her take the "eggs" to the roof of The Rose Tower hotel where she accidentally fell, yet still the egg dust was released and possessed 2'000 civilians on the beach below who surrounded Snowglobe 7 wanting to be let in so they could hand themselves over to be eaten. The Doctor accessed Snowglobe 7 with an ambulance and detonated the engine from the old Modrakanian's ship. This killed the Gappa and blew up Snowglobe7. (TDA: Snowglobe 7)