Sea urchins: Animal without eyes sees through entire body

Below is a piece of news that will make you slip in a state of surprise. If you thought that sea urchins were sightless because of the absence of eyes, then the research at the University of Gothenburg will prove you wrong. Researchers have found out that these sea creatures can see with the help of their entire body despite missing eyes. Wow!

Sea Urchin

To conduct the experiment, they took two different sized disks and positioned urchins in that area. The dark disks measured 6 cm and 9 cm, respectively and were placed in a brightly illuminated area. The urchins were placed near both disks to record their sensitivity towards light and in turn their sight. Researchers observed that all the 39 urchins ran towards the 9 cm disk and did not respond much to the 6 cm disk. Through this, the researchers led to the conclusion that these sea urchins had a visual resolution of approximately 10 deg.

Yerramilli and Johnsen further calculated the visual resolution keeping the urchin’s spine density in mind, which proved their resolution would be near about 8 deg. This means they can see larger objects easily, but may face difficulty spotting smaller ones. The findings have found a place in the scientific journal Proceedings of the National Academy of Sciences (PNAS) and The Journal of Experimental Biology.

Sea urchins:

Sea urchins or urchins are spiny marine creatures. They are members of Phylum Echinodermata. They are small marine animals, which are round in shape and are found near rocky shores specially at the bottom of the ocean or sea. They may be purple, green, white, brown, black, or red in color. Most of them are about three to ten centimeters across. They mostly feed on algae found in water. Triggerfish, sea otters, and wolf eels feed on them. Most of their body is covered with spines, which project out like a spear. They move with the help of tube-like adhesive feet that are very small, transparent and present in hundreds. Sea urchins use their feet to move like most other spiny-skinned creatures. They have a fleshy tongue and a mouth with five teeth or jaws.

Some Facts About Sea Urchins

Picture Gallery

Sea Urchin

Researchers at the University of Gothenburg have shown that sea urchins see with their entire body despite having no eyes at all.

Interesting Characteristics:

• These tiny sea creatures are blessed with adhesive tube feet that are of great help.
• Sea urchins were the first organisms in biology whose sperm cells fertilized the ovum. This embryonic development was visible with the help of a microscope that led to a lot of findings.
• Latest genome sequencing shows a link between sea urchin and vertebrate immune system-related genes. This will be of utmost help while learning evolution of innate immunity.
• Sea otters and wolf eels feed on sea urchins. They somehow destroy their surroundings when left free, which is called Urchin Barren. Such an area does not have any fauna or macroalgae.
• Sea urchins save themselves from predators with the help of their long and razor-sharp spine, which creates an aching injury when human skin gets pierced with it. But gladly, it is not poisonous.
• Gonads, also referred as their roe, are considered to be quite delicious and are a part of many scrumptious meals.
• Their spicules (pointed crystalline bones that are a part of the endoskeleton) look like the logo of Mercedes Benz in as less as 48 hours after fertilization. It develops at the larval stage and has an odd morphology.