Normal: "A spider that spits a debilitating web onto its prey before striking. If victory seems out of reach, you'd best run while you still can." Oversoul: "A fiend that extensively uses magic now that it's oversouled. Its nastiest ability involves gil. Bank on crying all the way home after this one." — Scan
The boss can inflict Stop on all party members simultaneously. His attacks aren't strong, but the Stop effect lasts for about five turns. His strongest attack when he is Oversouled and eats up a girl and spits them out.
To enter the Aeon Cup in the Coliseum, the player must capture and raise the story levels of eight special creatures. These creatures will immediately be available to be released upon capture, however, what the player has to do is raise their story levels by three and then release them. This will change that particular creature into an aeon. Aranea is one of these eight creatures, capable of being changed into Anima.
Aranea is the name of a genus of orb-weaver spiders, but the more likely origin for the name in the context of an RPG is the longstanding Dungeons and Dragons intelligent shapechanging spider race of that name.