Question

1. What does the iris and the ciliary body have in common?

2. What is the function of the tapetum lucidum, and what does the vertebrates who possess them typically have in common?

Answer 1

1. The iris and ciliary body has following things in common-

(i) The outer edge or part of the iris is known as root, which extends and is attached to the anterior ciliary body.

(ii) The iris along with the anterior ciliary body provide a pathway to drain out aqeous humour from the eye.

(iii) The iris along with the ciliary body constitutes the anterior uvea. Uvea controls many eye functions like adjusting the light levels, distance of objects etc.

2. Tapetum lucidum- The layer of tissue present in the choroid region of eyes exactly between the lens and retina , which is rich in guanine content. The main function of the tissue is to act as a reflective membrane and thus is responsible for eye-shine characteristic of many mammals. It helps to reflect back visible light through the retina , increasing the level of light to photoreceptors. Thus we can conclude that Tapetum lucidum contributes to enhanced visual sensitivity under low light/ dark conditions.

The vertebrates which have tapetum lucidum mainly the mammals, some reptiles , amphibians even invertebrates will have characteristic eye-shine color and accounts for superior night vision by providing enhanced visual sensitivity to the nocturnal animals.