Tone Killick
24 02 16 Zoropsis spinimana
Most spiders have eyes, and, while some have exceedingly good vision, in particular the Salticidae, Thomisidae and Lycosidae for others sight is not very important. Most spiders can detect polarised light which helps them to know where they are in the world. Most spiders have eight eyes, a few families have six (Dysderidae, Sicariidae, Oonopidae). Spiders have simple eyes, meaning there is just a single lens to each eye. They have primary and secondary eyes. In primary eyes the rhabdomeres (the light sensitive part of a visual cell in the retina) is toward the light. In secondary eyes the rhabdomeres face away from the light, (as they do in our eyes). Primary eyes have no tapetum (the reflective layer at the back of the eye that causes eye-shine in a cars headlights in cats and dogs), but secondary eyes do have a tapetum. There are three different types of secondary eyes and these can important in spider systematics.
24 02 16 Zoropsis spinimana
Most spiders have eyes, and, while some have exceedingly good vision, in particular the Salticidae, Thomisidae and Lycosidae for others sight is not very important. Most spiders can detect polarised light which helps them to know where they are in the world. Most spiders have eight eyes, a few families have six (Dysderidae, Sicariidae, Oonopidae). Spiders have simple eyes, meaning there is just a single lens to each eye. They have primary and secondary eyes. In primary eyes the rhabdomeres (the light sensitive part of a visual cell in the retina) is toward the light. In secondary eyes the rhabdomeres face away from the light, (as they do in our eyes). Primary eyes have no tapetum (the reflective layer at the back of the eye that causes eye-shine in a cars headlights in cats and dogs), but secondary eyes do have a tapetum. There are three different types of secondary eyes and these can important in spider systematics.