Featured Research

from universities, journals, and other organizations

Seeing Sea stars: The missing link in eye evolution?

Date:
July 5, 2013
Source:
Society for Experimental Biology
Summary:
A study has shown for the first time that sea stars (also known as starfish) use primitive eyes at the tip of their arms to visually navigate their environment. New research has shown that sea star eyes are image-forming and could be an essential stage in eye evolution.

The starfish compound eye (red cups) is seen at the tip of the arm. Each red cup corresponds to a single optical unit, ommatidium, in an arthropod compound eye.
Credit: Dan-Erik Nilsson, Lund University

A study has shown for the first time that starfish use primitive eyes at the tip of their arms to visually navigate their environment. Research headed by Dr. Anders Garm at the Marine Biological Section of the University of Copenhagen in Denmark, showed that starfish eyes are image-forming and could be an essential stage in eye evolution.

Related Articles


The researchers removed starfish with and without eyes from their food rich habitat, the coral reef, and placed them on the sand bottom one metre away, where they would starve. They monitored the starfishes' behaviour from the surface and found that while starfish with intact eyes head towards the direction of the reef, starfish without eyes walk randomly.

Dr Garm said: "The results show that the starfish nervous system must be able to process visual information, which points to a clear underestimation of the capacity found in the circular and somewhat dispersed central nervous system of echinoderms."

Analysing the morphology of the photoreceptors in the starfish eyes the researchers further confirmed that they constitute an intermediate state between the two large known groups of rhabdomeric and ciliary photoreceptors, in that they have both microvilli and a modified cilium.

Dr Garm added: "From an evolutionary point of view it is interesting because the morphology of the starfish eyes along with their optical quality (quality of the image) is close to the theoretical eye early in eye evolution when image formation first appeared. In this way it can help clarify what the first visual tasks were that drove this important step in eye evolution, namely navigation towards the preferred habitat using large stationary objects (here the reef)."

Most known starfish species possess a compound eye at the tip of each arm, which, except for the lack of true optics, resembles arthropod compound eye. Despite being known for about two centuries, no visually guided behaviour has ever been documented before.


Story Source:

The above story is based on materials provided by Society for Experimental Biology. Note: Materials may be edited for content and length.


Cite This Page:

Society for Experimental Biology. "Seeing Sea stars: The missing link in eye evolution?." ScienceDaily. ScienceDaily, 5 July 2013. <www.sciencedaily.com/releases/2013/07/130705101826.htm>.
Society for Experimental Biology. (2013, July 5). Seeing Sea stars: The missing link in eye evolution?. ScienceDaily. Retrieved March 6, 2015 from www.sciencedaily.com/releases/2013/07/130705101826.htm
Society for Experimental Biology. "Seeing Sea stars: The missing link in eye evolution?." ScienceDaily. www.sciencedaily.com/releases/2013/07/130705101826.htm (accessed March 6, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Friday, March 6, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Giant Panda Goes Walkabout in Southwest China

Giant Panda Goes Walkabout in Southwest China

AFP (Mar. 6, 2015) — A giant panda goes walkabout alone at night in southwest China. Duration: 00:37 Video provided by AFP
Powered by NewsLook.com
Lack of Snow Pushes Alaska Sled Dog Race North

Lack of Snow Pushes Alaska Sled Dog Race North

AP (Mar. 6, 2015) — A shortage of snow has forced Alaska&apos;s Iditarod Trail Sled Dog Race to move 300 miles north to Fairbanks. The ceremonial start through downtown Anchorage will take place this weekend, using snow stockpiled earlier this winter. (March 6) Video provided by AP
Powered by NewsLook.com
Praying Mantis Looks Long Before It Leaps

Praying Mantis Looks Long Before It Leaps

Reuters - Innovations Video Online (Mar. 5, 2015) — Slowed-down footage of the leaps of praying mantises show the insect&apos;s extraordinary precision, say researchers. Video provided by Reuters
Powered by NewsLook.com
Octopus Grabs Camera and Turns It Around On Photographer

Octopus Grabs Camera and Turns It Around On Photographer

Buzz60 (Mar. 5, 2015) — A photographer got the shot of a lifetime, or rather an octopus did, when it grabbed the camera and turned it around to take an amazing picture of the photographer. Jen Markham (@jenmarkham) has the story. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins