3 min learnNew DelhiAug 19, 2026 11:00 PM IST
Once we consider animals, we normally think about a physique with a clearly outlined head, full with eyes, a mouth, and a mind. Nonetheless, evolution has taken a really completely different path for some creatures.
A number of animals both lack a definite head altogether or have such a diffuse physique plan that it’s tough to establish one. But many nonetheless possess light-sensitive organs or totally developed eyes that assist them navigate, detect predators, or discover meals.
Listed below are 5 extraordinary examples.
Starfish
Regardless of their title, starfish don’t have a real head or mind. As an alternative, they’ve radial symmetry, which means their physique is organized round a central disc.
Every arm ends in a tiny eyespot that may detect gentle, shadows, and huge objects. Whereas these eyes can’t type detailed photographs, they assist starfish orient themselves and discover their manner again to coral reefs after wandering away.
Sea urchins
Sea urchins additionally lack a definite head, however scientists have found that they’ll “see” with out having standard eyes. Their our bodies comprise quite a few light-sensitive cells, and their lengthy spines assist block gentle from completely different instructions, successfully turning the complete physique right into a easy visible system. This enables sea urchins to detect approaching predators and navigate their surroundings.
Scallops
Scallops possess one of the vital uncommon visible techniques within the animal kingdom. As an alternative of getting a head, they’ve as much as 200 tiny, vivid blue eyes lining the sting of their mantle.
Every eye incorporates a mirror created from microscopic crystals that displays gentle onto the retina, a design hardly ever seen in nature. These eyes assist scallops detect motion and escape predators by quickly clapping their shells collectively to swim away.
Story continues beneath this advert
Moon jellyfish
Jellyfish haven’t any mind and no outlined head, but many species possess easy sensory buildings known as rhopalia. These comprise primitive eyes that detect adjustments in gentle depth and path. Though they can not see detailed photographs, these light-sensitive organs assist jellyfish keep their orientation within the water and respond to environmental changes.
Brittle stars
Shut relations of starfish, brittle stars additionally lack a definite head. As an alternative of counting on eyes positioned on the ends of their arms, many species have light-sensitive cells embedded all through their skeleton. This permits them to sense gentle and shadow throughout a lot of their physique, serving to them rapidly retreat into crevices when hazard approaches.
