Spider

From TARDIS Index File, the free Doctor Who reference.

The spider was a type of arachnid commonly found on Earth. They were noted for spinning webs which they used to catch prey.

Originally, spiders were small, inoffensive creatures, none growing much larger than a rat. By the 26th century, though, radiation had caused mutations, allowing them to reach much larger sizes. (NA: Ship of Fools) An example of this were the Eight Legs, spiders with great mental powers, who evolved on Metebelis III from spiders that survived the crash landing of a Human ship. (DW: Planet of the Spiders)