Featured Research

from universities, journals, and other organizations

'Seeing' without eyes: Hydra stinging cells respond to light

Date:
March 5, 2012
Source:
BioMed Central Limited
Summary:
In the absence of eyes, the fresh water polyp, Hydra magnipapillata, nevertheless reacts to light. They are diurnal, hunting during the day, and are known to move, looping end over end, or contract, in response to light. New research shows that stinging cells (cnidocytes) in hydra tentacles, which the animals use for self protection and to catch prey, are linked via a simple nervous system to primitive light responsive cells that co-ordinate the animals' feeding behavior.

Hydra opsin.
Credit: David Plachetzki

In the absence of eyes, the fresh water polyp, Hydra magnipapillata, nevertheless reacts to light. They are diurnal, hunting during the day, and are known to move, looping end over end, or contract, in response to light. New research published in BioMed Central's open access journal BMC Biology shows that stinging cells (cnidocytes) in hydra tentacles, which the animals use for self protection and to catch prey, are linked via a simple nervous system to primitive light responsive cells that co-ordinate the animals' feeding behavior.

Seeing without eyes: hydra stinging cells respond to light In the absence of eyes, the fresh water polyp, Hydra magnipapillata, nevertheless reacts to light. They are diurnal, hunting during the day, and are known to move, looping end over end, or contract, in response to light.

New research published in BioMed Central's open access journal BMC Biology shows that stinging cells (cnidocytes) in hydra tentacles, which the animals use for self protection and to catch prey, are linked via a simple nervous system to primitive light responsive cells that co-ordinate the animals' feeding behavior. 

Hydra are members of a family of radially symmetric animals (Cnidaria), all of which use specialized cnidocytes to catch prey. This family also includes well-known creatures such as jellyfish and corals, which, like other cnidarians, have the simple design of a mouth surrounded by tentacles. Hydra tentacles contain barbed, poison containing cnidocytes that they use to stun animals like the water flea, Daphnia, before eating them alive, and to protect themselves from attack by other animals.

Researchers from the University of California lead by Dr David Plachetzki have discovered that the light sensitive protein opsin found in sensory cells is able to regulate the firing of harpoon-like cnidocytes. These light sensitive neurons are found integrated into arsenals that include the stinging cnidocytes as well as desmoneme cnidocytes, used to grasp prey, and sticky isorhiza, which help the hydra to summersault at 10cm a day.

The linking of opsin to cnidocytes explains how hydra are able to respond to light even though they do not have eyes. Dr Plachetzki described how other proteins necessary for phototransduction are also present in the sensory cells. "Not only did we find opsin in the sensory neurons that connect to cnidocytes in the hydra, but we also found other components of phototransduction in these cells. These included cyclic nucleotide gated ion channels (CNG) required to transfer the signal and a hydra version of arrestin, which wipes the phototransduction slate clean for a second signal."

Dr Plachetzki continued, "We were also able to demonstrate that cnidocyte firing itself is effected by the light environment and that these effects are reversed when components of the phototransduction cascade are turned off." Cnidarians have been around for over 600 million years. However the hydra's simple approach to using light, to aid survival and increase their chances of catching prey, uses the same visual pathway as humans and hints at a common ancestor. 


Story Source:

The above story is based on materials provided by BioMed Central Limited. Note: Materials may be edited for content and length.


Journal Reference:

  1. David C Plachetzki, Caitlin R Fong and Todd H Oakley. Cnidocyte discharge is regulated by light and opsin-mediated phototransduction. BMC Biology, 2012 [link]

Cite This Page:

BioMed Central Limited. "'Seeing' without eyes: Hydra stinging cells respond to light." ScienceDaily. ScienceDaily, 5 March 2012. <www.sciencedaily.com/releases/2012/03/120305081421.htm>.
BioMed Central Limited. (2012, March 5). 'Seeing' without eyes: Hydra stinging cells respond to light. ScienceDaily. Retrieved September 14, 2014 from www.sciencedaily.com/releases/2012/03/120305081421.htm
BioMed Central Limited. "'Seeing' without eyes: Hydra stinging cells respond to light." ScienceDaily. www.sciencedaily.com/releases/2012/03/120305081421.htm (accessed September 14, 2014).

Share This



More Plants & Animals News

Sunday, September 14, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Conservationists Face Uphill PR Battle With New Shark Rules

Conservationists Face Uphill PR Battle With New Shark Rules

Newsy (Sep. 14, 2014) — New conservation measures for shark fishing face an uphill PR battle in the fight to slow shark extinction. Video provided by Newsy
Powered by NewsLook.com
Shocker: Journalists Are Utterly Addicted To Coffee

Shocker: Journalists Are Utterly Addicted To Coffee

Newsy (Sep. 13, 2014) — A U.K. survey found that journalists consumed the most amount of coffee, but that's only the tip of the coffee-related statistics iceberg. Video provided by Newsy
Powered by NewsLook.com
'Magic Mushrooms' Could Help Smokers Quit

'Magic Mushrooms' Could Help Smokers Quit

Newsy (Sep. 11, 2014) — In a small study, researchers found that the majority of long-time smokers quit after taking psilocybin pills and undergoing therapy sessions. Video provided by Newsy
Powered by NewsLook.com
Spinosaurus Could Be First Semi-Aquatic Dinosaur

Spinosaurus Could Be First Semi-Aquatic Dinosaur

Newsy (Sep. 11, 2014) — New research has shown that the Spinosaurus, the largest carnivorous dinosaur, might have been just as well suited for life in the water as on land. Video provided by Newsy
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:

More Coverage


Genetic Link Between Visual Pathways of Hydras and Humans Discovered

Mar. 5, 2012 — What good is half an eye? Evolutionary biologists studying the origins of vision get that question a lot, and new research points to a possible answer. New findings indicate that, even in the absence ... read more
from the past week

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