Wednesday, July 31, 2013

Caught in My Web: Whale and Dolphin Brains, Whale Hunts Dolphin, Behavioral Transmission, Bee Hotels and Horrific But True Duck Tales

Image by Luc Viatour at Wikimedia
From whale and dolphin brains and drama to insect living, this week's Caught in My Web runs the gamut. And I just couldn't resist adding a scientifically accurate (and completely inappropriate for small children) parody of the Duck Tales intro.
  1.  At Brain Metrics, Bradley Voytek tells us just how cool whale and dolphin brains really are at The Measure of a Whale.
  2. As long as we’re talking about cetaceans, here in the Daily Mail are some amazing images of an eight-ton orca leaping over a dolphin in a battle of predator and prey.
  3. The neuroecology blog discusses the transmission of behavior from colonies of harvester ants to other daughter colonies in Transmitting Behavior Between Groups.
  4. Over at Bug Blog, Africa Gómez talks about common species of bees that may use a bee hotel in Bee Hotel Guests.
  5. And finally, many like to think of ducks as waddling balls of feathered cuteness, but their behavior can be downright horrific. The crew at Animation Domination Hi-Def (ADHD) has gifted us with a scientifically accurate version of Duck Tales. WARNING: Once seen, this can never be unseen. Not appropriate for all viewers… or most any viewers for that matter.

Wednesday, July 24, 2013

Welcome Home to Wood Tick Acres!

Early last spring I was offered a new job and embarked on a search for a new home. We found a beautiful property: wooded acreage with a trout stream and spring-fed pond, all in a reasonable commuting distance. The potential of this forest sanctuary glistened even under feet of spring snow.

When we returned in the rains of early summer to collect our keys and move in, we found that the thaw had revealed our forest sanctuary to be a mosquito-infested swampy wetland, complete with this welcome sign:

 Ticks? In a wetland? You wouldn’t think ticks would do so well in the water… But think again.

Ticks, like spiders, are arachnids. They’re known for feeding on the blood of other animals, but in reality, they only do so three times in their life (once in each life stage). Between those three blood meals, they can live for months or even years without feeding. Their extremely low energy metabolism (only about 10% that of insects and spiders), waterproof “skin”, and cold hardiness give them the ability to hunker down and ride out a range of weather conditions. And anyone who has tried swimming or doing laundry as a means of getting rid of ticks knows they can withstand those pressures too.

Photo of ticks
in a jar by
Laura Fielden-Rechav.
Researchers Laura Fielden-Rechav, Lisa Knolhoff, Susan Villarreal and Philip Ryan from Truman State University tested how long wood ticks (also known as dog ticks) could survive while submerged in water. They did this by placing ticks in water-filled jars for up to three weeks. Every day they removed a few ticks from the jars and placed them on a piece of paper to see if they recovered. Amazingly, the ticks survived underwater for 11 days on average and some lasted as long as 15 days!

If ticks can live underwater for nearly two weeks, this suggests that either 1) they are holding their breath and do not need much oxygen or 2) they can somehow get oxygen out of the water. The researchers tested this by having another set of ticks in water-filled jars, but this water had less oxygen in it. These ticks survived underwater for only 7 days on average, which shows us that the ticks are getting and using oxygen from the water.

So how do air-breathing ticks get oxygen from water? Ticks, like most insects and many spiders, have a breathing system called a tracheal system. This is a system of branching gas-filled tubes that provide each cell in the body with access to the environmental gas and the oxygen it contains. The tracheal system connects with the environment through openings in the body wall called spiracles. This is a great system for breathing air, but not for breathing water. So many water-breathing insects have developed an additional system called a plastron. A plastron is typically a region of the body near the spiracles that has lots of tiny water-repelling hairs that trap air around the opening of the animal’s breathing system. As the animal uses up its body’s oxygen, the oxygen levels in this trapped air space decline and oxygen then diffuses from the water around the animal into this trapped air space. Once the oxygen in the plastron air space is restored, the animal can breathe it with its air-breathing tracheal system. It works kinda like a perpetually refilling oxygen tank for SCUBA divers (if something so cool even existed).

The picture on the left shows a wood tick under the microscope. Notice the large spiracles behind the hind legs. If you don't see them there, check out the red spots on the sketch on the right. Images by Laura Fielden-Rechav.

The researchers were curious whether wood ticks have a plastron system to help them survive underwater for long periods of time. Ticks have two spiracles located behind their hind legs (which means they breathe with their rear end, not with their face – This is why they can bury their face into another animal to eat a blood meal without suffocating). The researchers wanted to test if these spiracles may each have a plastron. A plastron system relies on water surface tension that is generated by the water-repelling hairs, so if you do something that reduces this surface tension, it should block a plastron from being able to function. Rubbing alcohol breaks surface tension. So the researchers submerged three different groups of ticks in water: one group was just submerged as-is; a second group had one spiracle wetted with alcohol before they were submerged in water; and a third group had both spiracles wetted with alcohol before they were submerged in water. The group with no alcohol on either spiracle lived several days longer than either of the groups with alcohol.

When the researchers looked at the ticks under a high-powered microscope, they did not see little hairs that are typical of plastrons, but they did see lots of pores that open into structured pockets of airspace. This structure could produce the surface tension needed for a plastron system to work. So based on their evidence that ticks with spiracles wetted with alcohol don’t live as long in water and the microscope images showing these air pockets, it looks like air-breathing wood ticks can survive for long periods of time underwater by breathing with a unique plastron system never before seen in another species.

Before you get too grossed out the next time you pull a tick off your dog, take a minute to appreciate the incredible ability of this hardy critter.

Want to know more? Check this out:

Fielden, L.J., Knolhoff, L.M., Villarreal, S.M., & Ryan, P. (2011). Underwater survival in the dog tick Dermacentor variabilis (Acari:Ixodidae) Journal of Insect Physiology, 57, 21-26 DOI: 10.1016/j.jinsphys.2010.08.009

Wednesday, July 17, 2013

The Laws of Attraction: Mangrove Killifish Style

A mangrove killifish. Photo by D. Scott Taylor at Wikimedia.
In the game of love, we typically think of males as being the showy courting sex and females being the coy choosy sex. But what if your species doesn't have the simple division of males and females?

Most populations of animal species (and most notably our own) are roughly half male and half female, so this is the standard we tend to accept as "normal". In this common system, males generally invest less in each potential offspring than do females (in physical resources, parental time and risk), so they can afford to make a few poor mate choices in favor of having more mates over time. Females, on the other hand, have a lot more to lose and benefit from being picky about whom they chose to mate with. But this half-male/half-female system is not the only way to divide reproductive responsibilities... And how these responsibilities are divided can dramatically affect who is choosing whom.

This week I am at Accumulating Glitches pondering how a species' mating system influences how choosy it is in picking a mate. Specifically, we think about mate choice in the mangrove killifish, a species with males and hermaphrodites, but no females. It's a quirky system (by our standards), but it works! Check it out here.

And to learn more, check this out:

Ellison, A., Jones, J., Inchley, C., & Consuegra, S. (2013). Choosy males could help explain androdioecy in a selfing fish The American Naturalist, 181 (6), 855-862 DOI: 10.1086/670304

Wednesday, July 10, 2013

Caught in My Web: Food vs. Sex, Recording Vibrations, Genital Distractions, Singing Dogs and Extreme Vision

Image by Luc Viatour at Wikimedia
This week will be the first of a new feature: Caught in My Web, a collection of recent articles, blog posts, videos and more that shed light on interesting aspects of animal physiology and behavior.

      1. There is often a tradeoff between food and sex. The Schneider Lab talks about the physiology of at what point a male will leave a meal to search for sex in Should I Stay or Should I Go? on the blog Sexandfoodand. To make things more interesting, the critters discussed are the nematode worms, C. elegans, and males are not seeking sex with females, but rather with hermaphrodites. And as a bonus, this article includes the best Harlem Shake video of all time!

      2. If you liked my article, Interrupting Insects, on how male treehoppers use vibrations to court females, you’ll love this first-hand account of what it is like to do this kind of research! In his blog Missouri Historian, Micah Fletcher, Micah recounts his experience studying these critters in Eavesdropping on a Silent Symphony.

      3. In ScienceNow, Helen Fields tells us how hawk moths giggle their genitals to prevent bats from catching and eating them in ScienceShot: Vibrating Genitals may Ward off Predators. A word of caution: If you are being chased by a hungry predator, try this at your own risk!

      4. In Expedition to Find the New Guinea Singing Dog: The Rarest Dog in the World in Running Ponies at Scientific American Blogs, Becky Crew interviews James ‘Mac’ McIntyre, a field zoologist planning an expedition to find and study the world’s most elusive dog species.

      5. And just for fun, here’s a video on extreme animal vision by Steve Rotfield Productions.

          Wednesday, July 3, 2013

          The Genetics of Drinking Like a Fish

          Image by J. Dncsn at Wikimedia Commons
          Among people, drug and alcohol addictions are the most prevalent preventable cause of death in the Western world. But not everyone that tries an addictive substance like alcohol, cigarettes, and addictive drugs becomes addicted to the point that it has a devastating effect on their life and health. People that do struggle with addiction commonly have less control over their impulsive behavior than those that do not, and it is likely that our genes play a role in these differences in both impulsivity and addictive behavior.

          Although each animal species has a unique set of traits that defines them as that species, there are also striking similarities between species. It is these similarities and differences that allow comparative physiologists to make inferences about human health based on knowledge of how different animal species function. An animal species that demonstrates an aspect of physiology and/or behavior similar to humans (and can thus provide substantial insight to human health and behavior) is called an animal model. One surprising yet useful model for impulsivity and substance addiction is the zebrafish.

          I am coming to get you! Zebrafish photo by Ray Crundwell provided by the Royal Society.
          Like humans, zebrafish are vertebrates (animals with backbones). This isn’t just a similarity in structure, but comes from the fact that we share many of the same genes. Not only do zebrafish have many of the same genes that we do, but they show similar variations in behavior, impulsivity, and responses to addictive substances. They can be trained to do tasks that require various levels of impulse control, they can be tested for their likelihood to seek rewarding things, and as a perk, they are transparent as babies and you can see their organs functioning right through them!

          If you’ve ever wondered if you’re more impulsive than a fish, now is your chance to find out! Researchers from the School of Biological and Chemical Science at Queen Mary University of London who study the genetics of impulsivity and addiction in zebrafish are showcasing their work at the Royal Society Summer Science Exhibition in London! The Royal Society Summer Science Exhibition is an annual fair of the most cutting-edge science the UK has to offer and it’s running this week from Tuesday the 2nd through Sunday the 7th. No science background is required to attend (exhibits are aimed for anyone over the age of 12) and it’s free!

          The Zebrafish Genetics Exhibit focuses on an impulsivity test called the five-choice discrimination task. In this task, a fish learns that a light will turn on in one of five chambers. If it swims to that chamber, it will get a food reward. But if it doesn’t wait for the light and swims to the wrong chamber, it gets nothing. The exhibit features a human-driven version of the task where you can test yourself, your children and your friends. Another way you can test your impulsivity is with the continuous performance task. This task involves continuously hitting a button when you see certain cues appear on a screen, but not hitting the button when an X appears. It may sound easy, but it is deceptively hard. Test yourself and see how you compare to the rest of the population!

          The Zebrafish Genetics Exhibit also has a microscope where you can look at the transparent zebrafish babies and see their little hearts beat. They even have some fish with fluorescently labeled proteins which allow you to see neurons (brain cells) with the neurotransmitters dopamine or serotonin. These are among the neurons thought to be involved in addiction. And if you have any questions, you can ask the scientists directly! Researchers Alistair Brock, Matteo Baiamonte, Matt Parker, and Helen Moore (get to know them here) will all be on hand to provide demonstrations and to answer questions.

          The Zebrafish Genetics Exhibit is just one of 24 exhibits. Other exhibits include Technology for Nature (a demonstration of how scientists can harness technology from the Information Age to help monitor and respond to environmental change and biodiversity loss), Sports Research (a display of how modern science can help athletes achieve their full potential), and Prehistoric Colours (an exhibit of color-producing fossilized structures that help scientists learn about the role of color in prehistoric animal communication). In addition to exhibits, there are events all week, including talks on cutting-edge science topics; a science cabaret of jokes, songs, demonstrations, videos, poetry and other performances; and hands-on activities and demonstrations.

          If you want to attend the Summer Science Exhibition, it is located at 6-9 Carlton House Terrace, London SW1Y 5AG. Directions and other details can be found here. And if you can’t get to London this week, you can still watch the scientist videos, ask the scientists any question you want online, and play the science-based video games. Take advantage of this great opportunity to interact directly with the leading scientists of today!

          Want to know more about zebrafish? Check these out:

          1. Parker, M.O., & Brennan, C.H. (2012). Zebrafish (Danio rerio) models of substance abuse: harnessing the capabilities Behaviour, 149, 1037-1062 DOI: 10.1163/1568539X-00003010

          2. Parker, M.O., Millington, M.E., Combe, F.J., & Brennan, C.H. (2012). Development and implementation of a three-choice serial reaction time task for zebrafish (Danio rerio) Behavioural Brain Research, 277, 73-80 DOI: 10.1016/j.bbr.2011.10.037

          3. Parker, M.O., Brock, A.J., Walton, R.T., & Brennan, C.H. (2013). The role of zebrafish (Danio rerio) in dissecting the genetics and neural circuits of executive function Frontiers in Neural Circuits, 7, 1-13 DOI: 10.3389/fncir.2013.00063