The ultimate packed lunch?

Heterotrophy or growing your own algae? Image: Scott Camazine/Wikimedia Commons.
Image: Scott Camazine/Wikimedia Commons.

Heterotrophy is so time-consuming: find prey, stalk prey, catch prey, con­sume prey… Preying all of the day and all of the night in some cases. How much more straight­for­ward if you could just syn­thes­ise your own food and avoid all of that rush­ing about. Well, this par­tic­u­lar cal­or­ific conun­drum was solved by plants many hun­dreds of mil­lions of years ago. But some anim­als have also cot­toned on to this idea of a ‘free lunch’. Arguably, the most spec­tac­u­lar example of such an alli­ance is that between het­ero­trophic polyps and auto­trophic zoox­an­thel­lae in coral reefs. Another – but entirely unsus­pec­ted – sym­bi­osis has recently been dis­covered between the Spotted Salamander (Ambystoma mac­u­latum) and a green alga (Oophila amblysto­matis), within the adult repro­duct­ive tracts of the former, by Ryan Kerney and col­leagues (PNAS 108: 6497–6502, 2011). An asso­ci­ation between the alga and eggs of amphi­bi­ans – and not just the spot­ted sala­man­der – has been known for some time where it been sug­ges­ted that the auto­troph sup­plies oxy­gen to an oth­er­wise hyp­oxic egg mass (e.g. Pinder and Friet, Journal of Experimental Biology 197: 17–30, 1994] and may in return bene­fit from amphi­bian nitro­gen­ous waste. But iden­ti­fic­a­tion of algal cells within the amphibian’s tis­sues was unex­pec­ted. This ‘asso­ci­ation’ – it is too early to say what sort of sym­bi­osis it might be or if the sala­man­der obtains food from the alga, but which is viewed as a unique rela­tion­ship between a ver­teb­rate and a euk­a­ryotic alga – poses many ques­tions relat­ing to cell–cell recog­ni­tion and pos­sible exchange of meta­bol­ites or DNA. And, like other sym­bi­oses, this new one raises fur­ther ques­tions con­cern­ing the role(s) of ‘help­ing hands’ in the course of evolution.

Nigel Chaffey. ORCID 0000-0002-4231-9082

Nigel is a botanist and full-time academic at Bath Spa University (Bath, near Bristol, UK). As News Editor for the Annals of Botany he contributes the monthly Plant Cuttings column to that august international botanical organ. His main goal is to inform (hopefully, in an educational, and entertaining way...) about plants and plant-people interactions.

1 Response

  1. AJ Cann says:

    While I can under­stand the asso­ci­ation with eggs, the asso­ci­ation of algal cells with adult sala­man­ders is extremely odd, espe­cially for almost fos­sor­ial spe­cies such as A. mac­u­latum which almost never expose them­selves to light (out­side of spawn­ing time). This sort of pos­sible sym­bi­osis might make sense in a few amphi­bia such as bufonids which do occa­sion­ally sun­bathe, but makes no sense to me in Ambystomids.

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