In subsequent citations, only use the first author's last name followed by et al. in the signal phrase or in parentheses. (Kernis et al., 1993). In et al. , et should not be followed by a period.
Transcript of Hammerhead Shark Eyes. Structure of Eye. The structure of a hammerhead sharks eye is very similar to the human eye, they have a cornea, lens, retina, pupil and iris. Their retina has both cone and rod cells, which means they can see light, dark, and colours.
Using mitochondrial DNA, a phylogenetic tree of the hammerhead sharks showed the winghead shark as its most basal member. As the winghead shark has proportionately the largest hammer of the hammerhead sharks, this suggests that the first ancestral hammerhead sharks also had large hammers.