Sources : Sea-spider

Isidore of Seville [7th century CE] (Etymologies, Book 12, 6:18): The weaver [aranea, literally “spider”] is a kind of fish so called because it strikes with its ear [auris]; for its ear has stingers with which it attacks. - [Barney, Lewis, et. al. translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Fish 7.15): The aranea is a kind of fish in the sea, as Isidore says, which, having spikes in its ear, strikes those who approach with its ear. But it signifies that those who, while their ears are itching to hear evil things about their nearest relations, they often strike them with a grievous wound. And therefore it is said: hedge your ears with thorns. - [Badke translation/paraphrase]