Photo Dr P Andreas Svensson

Scientists out at the Monasah University have stumbled onto an amazing discovery. It appears that male Australian desert goby fish are smart when it comes to getting in the sack. They tend to adapt their ways of thinking when females are scarce.

The goby fish devote an abundant amount of time, energy, and risk their lives looking for a mate. Previous studies have shown that the male gobies are more likely to court bigger females as they can carry more eggs than the smaller females.

However, our clever little goby fish knows when he is beat, and knows when to settle. A new study, recently published in the journal Behavioral Ecology and Sociobiology, shows that if the male goby finds himself with a lack of females in his area, he will go after any that he finds, regardless of how big they are.

Doctors Bob Wong, Topi Lehtonen and Andreas Svenson have expanded upon their previous studies by getting their hands on goby fish from Central Australia, and keeping their eyes on them, in controlled conditions of course.

Dr Bob Wong, who is a senior lecturer in the Science Faculty at the university, has commented that the study has indicated that when the male goby ran into more females, they were far more picky about who they mated with, and how much energy they would use in the attempt.

“By contrast, males will court females vigorously irrespective of her attractiveness if passing females are few and far between,” Dr Wong explained.

This just goes to show that the male goby “like big butts and they cannot lie”, but more importantly know when they are licked, and know that beggars cannot be choosers.

In several species of fish, such as the cichlid species Neolamprologus pulcher, it is common for subordinate females to help an unrelated dominant breeding pair raise their young. The reason behind this seemingly altruistic behaviour, known as alloparental care, has puzzled scientists for many years and one of the most widely spread hypotheses put forward has been the ‘pay-to-stay’ hypothesis. According to the ‘pay-to-stay’ rationale, the subordinate female helps out the dominant pair just to be able to stay in the group. Not being ostracised from the group augments her long-term survival chances, thus increasing the chance for her to live long enough to eventually obtain a breeding position.

Picture by: JJPhoto.dk

A new study carried out by Dik Heg and coauthors does however bring forth a new hypothesis: the substrate rationale. In their study, Heg and his colleges tested the hypothesis that subordinate female cichlids are helping dominant pairs in return for a more immediate direct reproductive benefit. After a series of experiments where the total number of eggs produced over a 30 day period by dominant and subordinate Neolamprologus pulcher females were carefully counted, researchers found that a subordinate female helping out a dominant pair was more likely to produce eggs herself compared to other subordinate females.

According to Heg and coauthors, the most likely reason for the increased reproductive success of “fish nannies” is that the subordinate female gains access to the breeding substrate.

If you wish to read more, see the paper “Heg, D, E Jutzeler, JS Mitchell and IM Hamilton (2009) Helpful female subordinate cichlids are more likely to reproduce”. It has been published in the journal PLoS ONE.

Here at AC Tropical Fish, we believe in the Jude Law-hypothesis. The dominant female will naturally snatch away the most prosperous male, but by posing as a benevolent nanny even a subordinate female can gain access to his home and hope for some of his triumphant DNA to eventually find its way into the genetic make up of her own offspring.

In an effort to curb the population of invasive Atlantic sea lampreys (Petromyzon marinus) in the North American Great Lakes, researchers are now testing a “love trap” in northern Michigan.

The traps will be scented with an odour produced by male lampreys during mating and researchers hope that this smelly love potion will lure female lampreys into the traps.

“We are trying to fool them into a fatal love,” said researcher Nick Johnson who will spend the next three years evaluating the effectiveness of the method.

The traps will be placed in ten streams around the Great Lakes, since lampreys swim into streams when it’s time to mate. After spawning, they die.

The Atlantic sea lamprey is native to the Atlantic Ocean but has been able to migrate into the Great Lakes through man-made shipping canals. The first specimens where seen in the region as early as the 1830s. By the 1950s, lampreys had decimated native populations of lake trout and white fish by rasping through their skin and sucking out their blood and bodily fluids. Several other populations of large and commercially important food fish had also been severely damaged by the new resident.

Since 1955, Fisheries and Oceans Canada and the U.S. Fish and Wildlife Service have worked closely on the Great Lakes Fishery Commission to control the Atlantic sea lampreys, using lampricides (substances toxic to lamprey larvae), migration barriers, and sterilization of male lampreys. Hopefully, the new pheromone scented traps will prove an efficient addition to their arsenal.

According to the journal Surgery, a 50 cm (20 in) eel was removed from a man’s rectum at the Kwong Wah Hospital in Kowloon, Hong Kong.

The 50-year old man was admitted to the Accident and Emergency Department complaining about abdominal pain.

European Eel – Picture by Ron Offermans; GNU

Doctors diagnosed him with peritonitis, inflammation of the peritoneum*, and did an x-ray to find out the underlying cause. Interestingly enough, what they saw on the x-ray was an eel stuck inside the man’s rectum.

The eel was still alive and biting the patient’s splenic flexure, which is a sharp bend located between the transverse and the descending colon. Doctors also found a 3 cm perforation over the anterior wall of the rectum.

“On further questioning,” says the paper, “the patient admitted an eel was inserted into the rectum in an attempt to relieve constipation. This may be related to a bizarre healthcare belief, inadvertent sexual behaviour, or criminal assault. However, the true reason may never be known.”

The patient was released from hospital a week later. We have been unable to find any information about what happened to the eel.

* The peritoneum is a serous membrane that forms the lining of the abdominal cavity or the coelom.

A lobster dinner is often perceived as the ultimate romantic meal, but while we happily utilize their bodies to promote our own chances of passionate encounters we actually know very little about the reproductive rituals that goes on deep down in the ocean. Did you for instance know that these super romantic creatures pee each other in the face before making sweet lobster love?

“Lobsters actually pee each other in the face to communicate” says researcher Malin Skog, a Ph.D. student at the University of Lund in Sweden that will be submitting her dissertation ”Sex and Violence in Lobsters – a Smelly Business” in September. Her research is focused on the importance of fighting and peeing when lobsters mate.

“I discovered that we hardly new anything about our lobster, despite the fact that it is such an important resource for the fishing industry” Malin Skog explains when asked about her peculiar interest in crustacean copulation.

By pairing up lobsters in aquariums, Malin Skog has been able to watch and film how males and females fight each other and how an encounter sometimes results in mating, sometimes in the male getting slapped and forced to retreat. This intricate behaviour seems to be controlled through scent particles excreted in urine. On a lobster, the olfactory organ (the “nose”) is located on the smaller pair of antennae on the head and the urine is also excreted from the head. So in order to communicate through scents, lobsters actually pee each other on the head.

During a lobster fight, the winning member will excrete a scent that means “I am stronger” while the loosing combatant will secrete a scent that says “I give up”. Fighting will not only take place between males and females; lobsters readily fight members of their own sex over food, shelter and general dominance. Regardless of sex, the most violent clashes occur when two individuals of similar size battle each other. Lobster fights can easily result in lost limbs, such as legs and antennae.

When a male lobster encounters a female, the meeting will start with a fight even if the couple is ready to breed. It seems as though the male doesn’t understand that he has found a female lobster until she starts emitting the “I am a girl”-scent. When he senses this scent, he will stop fighting and start walking around her instead, touching her and trying to tip her over on her back. (Lobsters mate in the missionary position, stomach to stomach.) Sometimes the female will readily approve to being flipped over, but in other cases she will object and if she stubbornly refuses to mate no mating will occur.

Sources:
Sex and Violence in Lobsters – a Smelly Business, Malin Skog, a Ph.D. Lund university, Sweden
Interview in sydsvenskan.se (in Swedish)