USA: salamander larvae try to get too big for predators

About this video:

We discovered this female spotted salamander ovipositing on a stick while conducting a vernal pool survey.

From New Scientist:

Greedy larvae too much of a mouthful for predators

* 11:29 28 August 2007

* Roxanne Khamsi

Gluttony may protect certain species of prey from predators, suggests a new study. Some salamander larvae seem to have evolved such that they actively overeat to avoid becoming a meal themselves, say researchers.

Once the larvae reach a certain size, they no longer fit in the mouths of their predators. And the new study found that the larvae were mostly likely to engage in this overeating behaviour in ponds where they faced the greatest number of predators.

Mark Urban of the National Center for Ecological Analysis and Synthesis in Santa Barbara, California, US, spent three years collecting data from 10 ponds in the northeast of the country.

All of the ponds contained the spotted salamander Ambystoma maculatum, but only some of them were also home to its primary predator, the bigger marbled salamander Ambystoma opacum.

Marbled salamander larvae can comfortably gulp down prey smaller than 3.3 millimetres. And, notably, at three weeks the body of a typical spotted salamander larva measures about this size in diameter at its thickest point, making it relatively easy to swallow.

Scientists have shown, however, that spotted salamander larvae in ponds with many marbled salamanders measure about 3.8 mm in diameter – they believe that these prey bulk up to avoid becoming dinner.

Salamandra salamandra: here.

Hybrid salamanders in the USA: here.

In 1888, a biologist called Henry Orr was collecting spotted salamander eggs from a small, swampy pool when he noticed that some of them were green. He wrote, “The internal membrane of each egg was coloured a uniform light green by the presence in the membrane of a large number of minute globular green Algae.” Orr decided that the eggs “present a remarkable case of symbiosis.” The salamanders and the algae co-existed in a mutually beneficial relationship: here. And here.

Spotted Salamander Egg Masses: here.

New survey work suggests that fewer than 1,200 Mexican axolotls remain in its last stronghold, the Xochimilco area of central Mexico: here.

5 thoughts on “USA: salamander larvae try to get too big for predators

  1. Salamander is world’s first photosynthetic vertebrate

    A solar salamander? Scientists find photosynthetic organisms living inside a vertebrate’s cells for the first time.

    By Bryan Nelson

    Tue, Aug 03 2010 at 2:49 AM EST 3 Comments

    SOLAR-MANDER: The spotted salamander’s embryos have symbiotic algae living inside them. (Photo: Wiki Commons/public domain)

    Scientists have long believed that only plants, algae, some bacteria, and a few invertebrates were capable of taking advantage of photosynthesis, which converts sunlight directly into energy. But now, for the first time, a photosynthetic vertebrate has been found, according to Nature.

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    The incredible creature is none other than the fairly common spotted salamander (Ambystoma maculatum). Ironically, the spotted salamander is not a new species for researchers, and it has long been known that the animal’s embryos share a symbiotic relationship with photosynthetic algae. That relationship, however, was always assumed to be an outside one, whereby the algae and the salamander work separately toward a fair exchange of resources.

    It turns out that researchers just weren’t looking closely enough. While studying a batch of salamander embryos, scientist Ryan Kerney of Dalhousie University saw something different than the prevailing dogma would suggest — a bright green color coming from inside their cells.

    That color usually indicates the presence of chlorophyll, which is the light-absorbing green pigment that makes photosynthesis possible.

    “On a lark, I decided to take a long-exposure fluorescent image of a pre-hatchling salamander embryo,” said Kerney. After backing that experiment up using transmission electron microscopy, he confirmed his suspicion. There were algal symbionts located inside the salamander cells.

    In fact, the symbiotic partners were often found bordering mitochondria, organelles responsible for generating a cell’s energy. Thus, it’s likely that the mitochondria were taking direct advantage of the oxygen and carbohydrate, byproducts of photosynthesis that were generated by the algae.

    The reason this discovery is surprising is because all vertebrates have what’s known as an adaptive immune system, which naturally destroys any foreign biological material found inside the cells. How the algae in the salamander’s cells bypass this defense is a mystery.

    Even more interesting, Kerney also discovered that algae is present in the oviducts of adult female spotted salamanders, where the embryos form in their sacs. This means that it’s possible symbiotic algae are passed from mother to offspring during reproduction.

    “I wonder if algae could be getting into the germ [sex] cells,” commented David Wake, from the University of California, Berkeley, who watched Kerney’s presentation. “That would really challenge the dogma [of vertebrate cells disposing of foreign biological material]. But why not?”

    Although this is the first time such a close co-existence with a photosynthetic organism has been found in a vertebrate, the discovery leaves open the question about if other animals might harbor similar traits.

    “I think that if people start looking, we may see many more examples,” said developmental biologist Daniel Buchholz.


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