London Zoo are appealing to fish keepers worldwide to try and find a mate for a critically endangered, tropical, and perhaps lonesome, species. With only three left in captivity, the search is becoming desperate.
Entries in fish (6)
Recently there has been elevated concern about the effect small increases of acidity in the world’s oceans have on some of the world’s most vulnerable marine species. A recent report has however provided some hopeful and promising new findings, suggesting many species may be well adapted to cope with acidity change.
Scientists at the University of Essex have helped design a robotic fish capable of monitoring pollution. The fish, which measures about 1.5m long, may be a little larger than its real-life counterparts, but the movements closely mimic them. This construct of carbon fibre and metal, dubbed ‘robo-fish’, is a machine capable of autonomously hunting down contamination in the water, and feeding this information back to the shore for analysis.
Scientists have recently discovered that the widely feared piranha, use sounds to communicate with one another in an attempt to intimidate rivals, instead of attacking them.
Dr Eric Parmentier, from the University of Liege, Belgium, previously studied sound production and communication in a variety of fish species including piranhas. This research discovered that piranhas made sounds, however was inconclusive as to why. Studies in this area suggest that a wide variety of fish use noises to attract potential mates, therefore the sounds made by piranhas could possibly indicate a reproduction process.
Through the use of hydrophones (underwater microphones), Dr Parmentier and his colleagues undertook a laboratory experiment that recorded the sounds piranhas made when they confronted each other, while also filming their interactions.
The recordings picked up three distinct sounds from the piranhas. The first was a bark that the fish produced when they “displayed” or confronted one another without engaging in fighting behaviour. The other two were a drum – like beat which they used when chasing one another and a softer croak made when biting other individuals. These physical confrontations tended to be made over food.
For much of the study the fish made no noise and did not engage in any passive or physical confrontations. It was only after hours of observations that researchers managed to capture this illusive behaviour.
The production of sound in piranhas is made by vibrating their swim bladders, a gas filled chamber that helps regulate their buoyancy. The vibration of the swim bladder is driven by high speed muscles that contract and relax 150 times every second.
Dr Parmentier suggests piranhas use noises to communicate as it uses less energy than physical conflicts. As a result, energy expenditure can be directed into other important biological activities such as reproduction and feeding.
Dr Parmentier and his team are aiming to conduct further studies on piranhas in the Amazon to find out more about the acoustic repertoire of this fascinating creature.
By Anthony Kubale
photo: Li Bo source: treehugger
A disturbing and cruel trend is emerging in China; keyrings containing live animals. The keyrings may contain one of three options for the discerning customer: one newt, one Brazil turtle or two small kingfish. Each keyring contains ‘nutrient rich water’ in varying choices of colour and can be bought for as little as £1.00. Of course, the water is not nutrient rich (tested by veterinarians) and the animals are contained in a small space until they die a few days later due to suffocation. But with prices this cheap, does it really matter to the customer if they die quickly when they can purchase more of them cheaply, ever increasing the demand?
The keyrings are sold openly in public areas due to this trade being completely legal in China as they are not ‘wild animals.’ Members of the general public acquire these keyrings perhaps as a ‘cool novelty’ or as one unidentified customer said “I'll hang it in my office, it looks nice and brings good luck.” Some well-wishers are unintentionally increasing demand as they are buying large quantities of keyrings and releasing the animals into the wild.
In addition to increasing demand, the released animals may cause additional problems to the ecosystem if animals are released in the wrong environments, resulting in competition for limited resources. Customers should also be aware of the health risks posed by the animals in the keyrings. For example, turtles are carriers of salmonella bacteria, which may be extremely harmful if individuals come in contact with it.
This obvious cruelty is becoming increasingly popular in China. Encouragingly, so is the global awareness of this trade, sparking campaigns to try and stop the sale of these keyrings immediately. If the general public of China use their better judgement, hopefully the demand will drop and the trend will decrease.
Sign the petition and help put an end to animal cruelty.
The rocky shoreline of Guam in Micronesia is home to one of the most unique but strange fish species, the Pacific leaping blenny (Alticus arnoldorum). Recent studies have revealed findings detailing this animal’s diverse and complex social lifestyle, as well as throwing new light on the transition from marine to terrestrial animals.
The Pacific leaping blenny is a marine fish, yet it is terrestrial in all aspects of its adult life. This causes the main constraint facing its terrestrial life, its ability to breath. Having no lungs, it relies on the exchange of oxygen and carbon dioxide via its gills and skin. Consequently, they must remain moist to avoid asphyxiation.
In a study led by Dr Terry Ord, of the UNSW Evolution and Ecology Research Centre, it was found that Pacific leaping blennies are heavily dependent on tide and temperature fluctuations, so much so, that almost all activity is restricted to mid tides when conditions are more favourable. The Pacific leaping blenny has never been observed voluntarily returning to the water. Instead, it actively avoids submersion from high tide or low tide waters by leaping along rocks and hiding in crevices above the waterline.
It is extremely agile when on land, moving quickly over rocky surfaces using a unique tail twisting behaviour. This is combined with an expanding pectoral and tail fin morphology that allows them to adhere to almost any film surface. Working with Toni Hsieh, of Temple University in the US, Dr Ord found that adult blennies use the brief window at mid tide to breed and socialise in a number of surprisingly complex ways.
It was noted that males are highly territorial, using complex visual displays such as vigorous head nodding and red coloured fins that both attracts females and warns off rivals (a process that is critical for reproductive success). Females tended not to be as territorial as males. However, they were found to aggressively defend their feeding territory at the start of their breeding season using red coloured fin displays that are usually more pronounced than males.
Little is known of breeding and development of young in Pacific leaping blennies but it has been suggested that females inspect a rock hole with the possibility of depositing eggs. After successfully deciding on a nesting site and laying eggs, the female plays no further role in parenting, leaving the male to guard the eggs.
Within the Blenniidae family there are two genera that are highly terrestrial (one of which includes the Pacific leaping blenny), associated genera that are amphibious and the rest fully aquatic. Remarkably, representatives of all these genera types can be found in and around Guam. The hope is that further studies will provide a unique opportunity to shed further light on how a water–land evolutionary transition in animals took place.
By Anthony Kubale