Water, water, every where, Nor any drop to drink.

I found this new finding interesting. ScienceDaily reports on a new study that shows that sea snakes drink fresh water.

Sea Snakes Seek Out Freshwater To Slake Thirst

Sea snakes may slither in saltwater, but they sip the sweet stuff. So concludes a University of Florida zoologist in a paper appearing this month in the online edition of the November/December issue of the journal Physiological and Biochemical Zoology.

Harvey Lillywhite says it has been the “long-standing dogma” that the roughly 60 species of venomous sea snakes worldwide satisfy their drinking needs by drinking seawater, with internal salt glands filtering and excreting the salt. Experiments with three species of captive sea kraits captured near Taiwan, however, found that the snakes refused to drink saltwater even if thirsty — and then would drink only freshwater or heavily diluted saltwater.

So, saltwater sea snakes can literately dehydrate while swimming in their natural environment. That means that they need to live fairly close to fresh water, which limits their possible habitat.

This is why I love the scientific process. It was thought that we knew how sea snakes slake their thirst, but someone still make sure to investigate the subject, and thus proved the common assumption wrong.

The study can be found here (unfortunately behind a pay-wall)

For more information about the sea snakes, I recommend the wikipedia entry on the subject

I've heard about omnipresent but omnidirectional?

PLoS Biology brings us the news about a discovery of an omnidirectional fish. The black ghost knifefish (Apteronotus albifrons) uses a weak electric field to actively monitor its surrounding. This sort of monitoring is different from the ones that we usually see in that it's active, rather than passive (which we humans engage in).

PLoS Biology has been nice enough to write an synopsis about this discovery. That makes it a lot easier for us non-biologists to understand the meaning of the original article (excellent as that might be). The articles own authors' summary isn't too bad though

Most animals, including humans, have sensory and motor capabilities that are biased in the forward direction. The black ghost knifefish, a nocturnal, weakly electric fish from the Amazon, is an interesting exception to this general rule. We demonstrate that these fish have sensing and motor capabilities that are omnidirectional. By combining video analysis of prey capture trajectories with computational modeling of the fish's electrosensory capabilities, we were able to quantify and compare the 3-D volumes for sensation and movement. We found that the volume in which prey are detected is similar in size to the volume needed by the fish to stop. We suggest that this coupling may arise from constraints that the animal faces when using self-generated energy to probe its environment. This is similar to the way in which the angular coverage and range of an automobile's headlights are designed to match certain motion characteristics of the vehicle, such as its typical cruising speed, turning angle, and stopping distance. We suggest that the degree of overlap between sensory and movement volumes can provide insight into the types of control strategies that are best suited for guiding behavior.

So, we're dealing with a fish that can sense in all directions, and then move in any direction where it might locate prey. That sounds like a pretty good advantage to have while hunting (or escaping for that matter). So, why doesn't all, or at least a large number, of animals have this ability? Well, first of all, they would have to been maritime, as they need water for the electric field. Second of all, such things comes at a cost. As the summary clearly states.

Although it's certainly useful to be able to sense in all directions, active sensing comes at a cost; energetically, it's very expensive to generate a good-sized electric field, since the signal falls off rapidly with distance.

Obviously, this leads to a shorter detection range - according to the findings, the black ghost knifefish had a averagee estimated prey detection distance of about 3.5 cm from the fish's body. Hardly a substitute for good eyes in areas with sparse food resources.

Naming rights for 10 fish species sold for $2 million

This sounds like crass commercializing, but it's for a good cause.

Auction to Name Fish Species Nets $2 Million for Conservation

An auction of rights to name 10 newly discovered species of fish raised more than $2 million for conservation efforts in eastern Indonesia on Thursday night, setting a record for an event of its type.

The black-tie soiree, hosted by Prince Albert II and sponsored by Conservation International and the Monaco-Asia Society, featured species found last year in the Bird's Head Seascape, an area in the northwest corner of Indonesian Papua. Prices for the naming rights ranged from $500,000 for a Hemiscyllium shark from Cendrawasih Bay to $50,000 for the Pseudanthias fairy basslet. The identities of the winning bidders, and the names they chose, were not immediately disclosed.

I am of two minds over this. On the one hand, I must admit that I find the idea of buying the rights to naming animals somewhat repulsive. On the other hand, I realize how much good $2 million will do for conservation. And I am sure that the naming of animals take into consideration any sponsors an expedition have (much like geographical naming did in old days).

One good thing is that the bidders "had to pledge that they would name the species after people rather than corporate entities."

Did the Tasmanian Tiger loose to the Dingos?

Via a comment to one of PZ's posts over at Pharyngula, I came across this piece of news. Unfortunately I can't find the comment where the link was posted, so I can't give proper credit to the orginal poster.

Tasmanian tiger's weaker bite gave dingoes the edge

The Tasmanian tiger probably died out because of competition from the dingo, whose stronger head and neck could better handle the stresses of tackling bigger prey, according to research on the animals’ skulls. The new study challenges the theory that humans were mainly to blame.

First of all, I dislike the mis-use of the word "theory" here. It was at best a hypothesis, which was considered as one possible explanaition (the other hypothesis was that the extinction was caused by the Dingos). So the findings are not quite as revolutionary as the lead paragraph makes it sound.

What I find quite interesting about this study, is that it's based upon some computer models, where the scientists modelled the skulls of Dingos and Tasmanian Tigers.

Using a series of CT scans of the skulls, they created sophisticated computer models of the animals' heads. They then studied the stresses on the skull, jaw, teeth, and muscles around the skulls while they simulated the biting, tearing and shaking of prey.

They found that as the size of a struggling prey animal got bigger, so too did stresses at the back of both the skulls. But differences in skull geometry, and the amount of muscle that would have been attached to the back, meant that these stresses were relatively much higher in the thylacine.

So, in other words, Dingos could hunt larger animals than Tasmanian Tigers. Combined with the later's larger size (according to the article, they were 70% heavier than dingos), and there is a distinct evolutionary advantage to the Dingos.

The study can be found behind a pay-wall at the Proceedings of the Royal Society, though a abstract can be read here

Generalized reciprocity between rats demonstrated

PLoS Biology has an article about some experiments with cooperation between rats that showed that rats that had been helped by others before were more willing to help others, regardless of who those others were. In other words, they seemed to behave according to the old principle "what comes around, goes around".

Generalized Reciprocity in Rats by Claudia Rutte, Michael Taborsky

The evolution of cooperation among nonrelatives has been explained by direct, indirect, and strong reciprocity. Animals should base the decision to help others on expected future help, which they may judge from past behavior of their partner. Although many examples of cooperative behavior exist in nature where reciprocity may be involved, experimental evidence for strategies predicted by direct reciprocity models remains controversial; and indirect and strong reciprocity have been found only in humans so far. Here we show experimentally that cooperative behavior of female rats is influenced by prior receipt of help, irrespective of the identity of the partner. Rats that were trained in an instrumental cooperative task (pulling a stick in order to produce food for a partner) pulled more often for an unknown partner after they were helped than if they had not received help before. This alternative mechanism, called generalized reciprocity, requires no specific knowledge about the partner and may promote the evolution of cooperation among unfamiliar nonrelatives.

The authors sums up the finding pretty well, and I see no real need to elaborate on the findings

Author Summary

The evolution of cooperation is based on four general mechanisms: mutualism, where an action benefits all partners directly; kin selection, where related individuals are supported; “green beard” altruism that is based on a genetic correlation between altruism genes and respective markers; and reciprocal altruism, where helpful acts are contingent upon the likelihood of getting help in return. The latter mechanism is intriguing because it is prone to exploitation. In theory, reciprocal altruism may evolve by direct, indirect, “strong,” and generalized reciprocity. Apart from direct reciprocity, where individuals base their behavior towards a partner on that partner's previous behavior towards themselves, and which works under only highly restrictive conditions, no other mechanism for reciprocity has been demonstrated among conspecifics in nonhuman animals. Here, we tested the propensity of wild-type Norway rats to help unknown conspecifics in response to help received from other unknown partners in an instrumental cooperative task. Anonymous receipt of help increased their propensity to help by more than 20%, revealing that nonhuman animals may indeed show generalized reciprocity. This mechanism causes altruistic behavior by previous social experience irrespective of partner identity. Generalized reciprocity is hence much simpler and therefore more likely to be important in nature than other reciprocity mechanisms.

Of course, it's not possible to say if this behavior is abnormal, until similar tests have been carried out on other species. It does, however, tell us that it is possible that such behavior happens in nature, which is something that has only been speculated about before.

Need I say what this would mean regarding the percepted uniqueness of human altruism? If generalized reciprocity is the norm, then altruism would make evolutionary sense on a species level, and should be quite comment in nature (and it has been observed before among several species, so that supports this idea).