When we look into a mirror, we see a reflection of ourselves. As humans, we are aware that this is only a reflection and not actually another living person. However, very few animal species are able to acknowledge that their reflection is not another one of their species which could pose a threat to them. Capuchin monkeys, grey parrots, and elephants are among the few that are able to recognize their mirror image. A majority of animal species, including fish, treat the image in the mirror as a conspecific. As a result, it would make sense that a mirror test could be a good indicator of aggression, especially in fish. However, Valentina Balzarini and colleagues questioned this widespread method, noting recent studies which had shown that hormonal and gene expression responses differed between the fish being exposed to a conspecific or a reflection of itself.
It seems inevitable: the end-of-year lists. And yes, here at the Noldus blog, you can find them too. I did not want leave 2013 behind us without mentioning our three most popular blog posts on animal behavior research of this year. While 13 might not be a lucky number for some, we have had a great year in which we saw a lot of growth in zebrafish research and the combination of optogenetics and behavior. Not surprisingly, these two topics showed up in our top 3.
Topics: EthoVision XT, mice, Video tracking, The Observer XT, animal behavior research, video observation, fish, zebrafish, Danio rerio, DanioVision, Parkinson's Disease, rats, birds, CatWalk XT, gait analysis, arthritis, monkey, locomotion, 2013
Do you attend conferences? Imagine networking with 30,000 fellow neuroscientists in beautiful San Diego, California. Now add the sun-soaked beaches (yes, even in November), a 0% chance of rain, many social events, and 15,000 scientific presentations: that’s why you should attend Neuroscience 2013! Not convinced yet? Here are 10 reasons why you should attend Neuroscience 2013!
(1) Beautiful San Diego
Topics: EthoVision XT, mice, Video tracking, The Observer XT, fish, drosophila, zebrafish, DanioVision, Track3D, Tracking insects, Animal 3D tracking, open field test, CatWalk XT, PhenoTyper, T-maze, bottom dwelling, top 10, neuroscience, SfN
In this post I am looking back at our most popular posts (based on numbers of views) on video tracking. Zebrafish, optogenetics, and Parkinson’s disease are topics that dominate the list, which honestly is no surprise to me. Let me tell you about these 5 posts that are definitely worth a read if you are interested in video tracking research!
At five is Zebrafish with Parkinson’s
Fascinating life cycle
European eels (Anguilla anguilla) have a life cycle in which both larvae and adults travel incredible distances. The eggs hatch in the Sargasso Sea near North America and the larvae swim all the way to Europe. Near the European estuaries (the coastal areas with brackish water) they transform into the so-called glass eels that are transparent and approximately 8 cm in size. These glass eels enter the estuaries and move upstream in the fresh water, overcoming all sorts of natural challenges and tackling many obstacles to reach the waters where they will grow up. Then after 5 to 20 years, they mature and make the entire difficult journey back to the Sargasso Sea to spawn and die [1,2].
Having a choice for a mating partner is extremely important for females, so they can be critical in choosing which male to mate with. However, being critical also has its disadvantages; it costs time, energy, and may subject the females to an increased mortality risk (for example due to a higher predation risk. Therefore, being critical about a potential mating partner only pays off when males are abundant or when the risk of being critical is not too high. There are animals, such as green swordtail fish , which change their mating preference when predation risk becomes higher or when the mating season is nearing its end.
Often in animal research, animals with a certain genetic alteration are compared to a “wild-type” (this being the ‘normal’ rat, mouse, or zebrafish). One might assume that there is no difference between one wild-type animal and the next, but in fact, many different strains of wild-type animals are used.
Many wild-type zebrafish strains
The same is true for zebrafish. Many studies talk of wild-type animals, but the strain is not always mentioned. Furthermore, wild-type fish can be acquired at the pet shop, from a commercial scientific supplier, or simply caught in the wild. Vignet et al. noticed that there have been reports of differences in behavior between wild-type strains, and therefore they stress the importance of matching the most appropriate strain to the behavioral test.
Topics: EthoVision XT, Video tracking, fish, zebrafish, exploratory behavior, learning and memory, anxiety research, circadian rhytmicity, T-maze, color discrimination, novel tank test, light/dark challenge, bottom dwelling
Before starting something new, we tend to make sure that we are well-rested and conserving energy for what lies ahead. Fish are the same way, particularly Neolamprologus pulcher, a type of cichlid fish found in Lake Tanganyika, East Africa. There are two options for subordinate N. pulcher fish to take after they reach sexual maturity – they can choose to wait in line to inherit the dominant breeding position of the group or they can disperse and reproduce independently of the group. Other studies have been done researching dispersal and inheritance of the breeder position, including a study on paper wasps. However, this study, unlike the study on cichlids, did not account for whether dispersal was successful. Other studies also looked at defense in terms of future fitness – defending the entire group rather than just the individual for the future success of that group, such as is the case with meerkats.
It’s a question of stay or go.
Scientists took a look at cichlid fish colonies for two types of subordinate fish: territory inheritors and dispersers. They were particularly interested in the long-term and short-term behavior of each type of subordinate fish before the dispersers left the group for other breeding opportunities. According to the researchers, the fish that would inherit the environment should show high investment in their territory (especially when it came to defense) and the fish that would disperse should reduce the amount of energy they invested in defense and other group aspects. They also predicted that cichlids that had decided to disperse would differ in behavior from those inheriting the breeding position before territory inheritance or dispersal.