Just Another Day (A Guest Post)

By Cassie Apostolou

The zooplankton picture on the left was provided by the EPA at Wikimedia Commons.
The human picture on the right was provided by Cassie Apostolou.

Check out the two pictures above. It doesn’t look like those two animals share a lot in common, right? Obviously the two organisms don’t look alike and the zooplankton (the odd looking microorganism creature in the left picture) lives in water and us humans typically like to stay dry on land. But if you dig a little deeper than just what you see, you’ll notice that most humans (probably you too) tend to endure specific daily migration patterns just as these little creatures do as well. Curious? Or maybe even offended that I pretty much just compared you to a zooplankton? Then continue reading and obtain the information you can throw in a friend’s face next time they are on an ego trip!

Whether you are in school or have a job, I’m sure you have a daily schedule you stick to. A daily example most people can relate to is this: you wake up to the annoying beeping of your alarm, maybe take a shower, change clothes, eat some breakfast, and then are headed off to work or school, you stay there for so many hours and then turn around and head on home (probably even taking the same routes most days too!) Well, as we do this on a daily basis, many zooplankton have a regular schedule too.


Photo of drifting zooplankton by
NOAA at Wikimedia Commons.

Zooplankton means “animal/water drifters”. Most get this name from performing daily vertical migrations cycles by floating or swimming to the surfaces of waters at night, while during the day time they stay in deeper depths of the waters. Why do they do this though? Well, research has shown that some zooplankton perform these daily cycles to escape fish predators and to obtain their food source. Also, daily migration occurs for the prevention of solar damage (just like humans and sunburn). There is also current research testing if metabolic advantages are also a cause for these migration patterns. Furthermore, studies have looked into external changes (such as temperature, salinity, and even acidity changes) as being a reason.

Photo of zooplankton under the microscope
by Ma.C. Mingorance Rodriguez at Wikimedia.

How do these animals with hardly any external features perform these day-to-day migrations? These creatures have to be in good physical shape to out-swim the predators. Also, they have to be able to adapt to the changing temperatures due to the sun or even the temperature changes in their environment. Plus, they have to be able to swim within a large group of other zooplankton to push against the ocean factors. Lastly, the zooplankton that perform the daily migrations are physically able to do so because some have evolved a pseudopodia (aka “false feet”) or flagella (tail like structure) adaption to help them move.

Still think you are way different than a zooplankton? Well, don’t you return to a safe area at the end of the night? I’m sure you eat at certain times and not at others and the food you get is mainly from the same places (probably your refrigerator or favorite restaurant). So in the end aren’t we all just walking around to obtain the necessities we need in life, just like zooplankton? I think when it comes down to the basics yes, but humans have put their own twists on life too.


References:

1. Forward, R.B. Diel Vertical Migration: Zooplankton Photobiology and Behaviour. in Oceanography and Marine Biology Vol. 26, ed. H. Barnes and M. Barnes, Aberdeen University Press, 1988, 361- 393.

2. Haney, J.F. (1988). Diel Patterns of Zooplankton Behavior Bulletin of Marine Science, 43 (3), 583-603

3. Iwasa, Y (1982). Vertical Migration of Zooplankton: A Game Between Predator and Prey The American Naturalist, 120 (2), 171-180 DOI: 10.1086/283980

Hiding in Plain Sight



The fish on the far left is a juvenile cleaner wrasse in the act of cleaning another fish. The two fish in the middle and on the right are both bluestriped fangblennies, one in its cleaner wrasse-mimicking coloration (middle) and the other not (right). Figure from the Cheney, 2013 article in Behavioral Ecology.

Sometimes the best place to hide is right under everybody's nose. If you look like you are innocuous and you belong there, every so often you can get away with trouble.

The bluestriped fangblenny, a coral reef fish in Australia and Indonesia, takes this mimicry strategy to a whole new level. The bluestriped fangblenny doesn't simply look like another species, but it can change its look to resemble any of three different species, depending on who happens to be around! When surrounded by olive-colored damselfish, they take on an olive hue. When surrounded by yellow anthias, they turn orangey-yellow. But their most impressive costume is that of the black and blue striped juvenile cleaner wrasse. And when they are not around a species they mimic, they revert to a brown shade and hide.

This week at Accumulating Glitches I talk about how the bluestriped fangblenny uses mimicry of juvenile cleaner wrasse to sneak up on an bite their predators! Check it out here.

And to learn more, check these out:

1. Cheney, K.L. (2013). Cleaner fish coloration decreases predation risk in aggressive fangblenny mimics Behavioral Ecology, 24 (5), 1161-1165 DOI: 10.1093/beheco/art043

2. Cheney, K.L., Skogh, C., Hart, N.S., & Marshall, N.J. (2009). Mimicry, colour forms and spectral sensitivity of the bluestriped fangblenny, Plagiotremus rhinorhynchos Proceedings of the Royal Society B, 276, 1565-1573 DOI: 10.1098/rspb.2008.1819

With a Fish in Your Pooper, Things Are Never Super (A Guest Post)

By Brittanie Delorit


You’ve probably heard of relationships between animals before: fish hitching a ride with a shark, clown fish hanging out in their anemones, or barnacles clinging to the fins of whales as they go for a swim; These are all unique in their own way. But have you ever heard of a fish living in the butt of another animal?

A Thelenota ananas sea cucumber
(one of the species used in this study).
Photo by Leonard Low at Wikimedia.

The sea cucumber, an echinoderm (along with sea urchins and sea stars), is found in shallow, sandy areas in all the world’s oceans. They eat by gulping in sand through their mouth, extracting decaying organic matter through their digestive tract and then excreting all of the unused matter from their anus. As if the way they eat isn’t strange enough, even more strange is the fact that sea cucumbers breathe using their anus. The sea cucumber gulps in water through its anus taking the oxygen out of the water… and that’s where the pearlfish come in, literally!

Several undergraduate scientists, Brooke Luciano, Ashleigh Lyman, Selena McMillian, and Abby Nickels, from the University of California in Santa Cruz, were on a Marine Ecology field course in French Polynesia. As part of their semester abroad, they wanted to study the interactions of pearlfish and their host, the sea cucumber. They focused their study on four main questions: 1) Is there competition to find a host?, 2) Is the pearlfish host specific and do they return to their original host after leaving?, 3) When the pearlfish finds a host are association cues present between the two?, and 4) Is the pearlfish nocturnally active?

To find results to their five hypotheses, studies were conducted. Two species of sea cucumbers were collected from sites outside of Opunohu Bay on the island of Moorea in French Polynesia. To remove the pearlfish from the sea cucumbers, the cucumbers were placed in a shallow, oxygen depleted container of water.

To answer the first question (Is there competition to find a host?), the pearlfish and the sea cucumber it inhabited were both tagged and observed to see if any fighting occurred between pearlfish. They also recorded if and when a pearlfish chose a different host to inhabit. Once they observed an incident of two male pearlfish fighting to the death inside a sea cucumber and resorting to cannibalism inside the cucumber. They also saw a pearlfish eating its way out of the sea cucumber it was inhabiting.

  It's reported that most pearlfish enter tail-first, like in this video. 

But cases of pearlfish entering head-first have been reported.

To answer the second question (Is the pearlfish host specific and do they return to their original host after leaving?), the pearlfish were tagged and then placed into a tank with multiple sea cucumbers including their present host. They then observed which cucumber they chose to inhabit, if they returned to it, and for how long. Conducting these studies concluded that no selectivity was found while observing the fish; most fish inhabited the first cucumber they came across even if it wasn’t theirs.

To answer the third question (When the pearlfish finds a host are association cues present between the two?), observations of the fish interacting with a potential host were recorded. Pearlfish smelling the length of their potential host was observed before actually entering the anus of the cucumber were recorded. The pearlfish were also observed listening along the sides of the cucumber, checking for another pearlfish already inside, and after checking, the pearlfish performed a type of knocking around the anus, encouraging its entrance into the body cavity of the cucumber. The sea cumber needs to open its anus to allow entrance for the pearlfish.

To answer the fourth question (Is the pearlfish nocturnally active?), night observations were done. But observations done at night showed no nocturnal behavior. This is strange because in the wild it has been observed that pearlfish live in the cucumber during the day, using them for protection, and then emerge at night to feed and scavenge. The reason no nocturnal behavior was observed in this study is thought to be because the pearlfish were under stress.

The relationship between pearlfishes and their sea cucumber hosts is one of the more intriguing cases of parasitism in the fish world. So if you happen to be a sea cucumber, make sure to hold your breath the next time you see a pearlfish swimming your way!


Article:
Luciano, B., Lyman, A., McMillian, S., Nickels., A. 2002. The symbiotic relationship between Sea cucumbers (Holothuriidae) and Pearlfish (Carapidae). A project of the Marine Ecology Field Quarter at the University of California, Santa Cruz, pgs 1-8. Available online: http://bio.classes.ucsc.edu/bio162/Previous%20Class%20Material/Moorea%202002/Readings/cucumbers.pdf

Who Said What? (A Guest Post)

By Porscha Carriveau




A Quaker parrot shows off his beak
and tongue. Photo by Alex Nelson
at Wikimedia Commons.

As an aviculturist-turned-scientist, to me, it is common sense to tell people that birds are heard more often than seen. People study bird songs or calls for a variety of reasons. The reason I study bird songs is to identify the songs that my African grey parrot has learned to mimic. His repertoire includes the vocalizations of several birds’ songs such as robins, cardinals, cat birds, and chickadees. He also mimics humans. When leaving home in the morning, the last thing that I hear heading out the door is "gotta go to work" and the sound of being blown a kiss. Most people would think nothing of it, but I am being told this by a bird that has no lips.

Here is an example of an African grey parrot producing sound :

Humans produce sound by using their vocal tract, which includes the larynx (known as the voice box), where the vocal folds are located. Sound is produced with the help of the trachea, which controls air flow through the larynx. In the larynx the vocal folds make sound by vibrating. The remainder of the vocal tract includes the throat, nose, tongue and lips which are involved in the articulation of speech. On the other hand, parrots have a syrinx (what rivals the larynx), a trachea, a tongue and a beak. This means that birds do not have vocal cords to produce the sounds that we as humans make; they instead have two air passages that come together at the organ known as the syrinx creating a vibration that produces sound.

From my experiences working with and owning a variety of parrots, I would say that African grey parrots and monk parakeets (also known as Quaker parrots) are the two clearest and best mimicking parrots. Quaker parrots originate from South America. Over the years these birds have learned to adapt to their environment extremely well, leading to the birds becoming an invasive species in many parts of the world, including several U.S. states where they are now illegal to own as pets.

Research done by Verena Ohms, Gabriël Beckers, Carel ten Cate and Roderick Suthers recently set up a study using x-ray imaging to determine what is taking place in the vocal tract of a Quaker parrot while producing species specific calls. To do this, a piece of metal wire was placed on the underside of a Quaker parrot’s tongue and two pieces of wire were placed inside the trachea attached to tracheal rings. Here is an example of what researchers were looking at which allowed them to monitor the bird’s tongue, beak, and trachea movements.

Researchers looked specifically at a few measures when a bird produces sound: the bird’s tongue height (TH), the size of the beak opening (BO), and the amount of tracheal stretching (TS).

Diagram of the measures taken from Quaker parrots. Figure from Ohms, et al., 2012.

Through observing the changes that occurred from the metal wires placed inside a Quaker parrot’s tongue and trachea while producing calls, researchers were able to conclude that a parrot's tongue functions much differently than a songbirds’. Even more amazing is that a parrot’s tongue is similar to a human tongue in the way that it is manipulated while producing sound. Researchers also determined that these parrots manipulate the sound frequency (pitch) of their calls by moving their tongues in and out. The researchers were also the first to observe a circle-like movement in the trachea that had not been described before in this species.

So whether my trouble-making parrot (you should hear him burp and excuse himself) is blowing me a kiss or mimicking a bird song, there are many similarities in the way that humans and parrots produce speech sounds. This is pretty amazing for two groups of animals that are so different!


Work Cited

Ohms, V., Beckers, G., Ten Cate, C., & Suthers, R. (2012). Vocal Tract Articulation Revisited: The Case of the Monk Parakeet The Journal of Experimental Biology, 215, 85-92 DOI: 10.1242/jeb.064717