Fido’s Big Feat, Smelly Hyena Sex, and the Decline of Darwin’s Frogs

Fido’s Big Feat: Human Communication

By Bio 94 Student Megan Ha

You have had a long day from school or work, or maybe both. You pull up to your house drained, mentally and physically, but when you open the door, you forget it because your furry friend is ecstatic to see you and greets you with slobbery kisses. The fact that your dog can relieve even a little bit of stress is due to that strong loving bond you two share, similar to that of a mother and child. Many people say dogs are therapeutic companions, but are they really? Science says yes! There is biological evidence supporting this. Higher levels of oxytocin have been found in urine of individuals with strong bonds with their dogs. Oxytocin is a hormone important in the bonding between mother and child, and when given to animals (including humans), aid in relaxation and coping with stress. However, dogs were not always bred for companionship. So where did man’s best friend come from?

Dogs, But Not Wolves, Use Humans As Tools (Photo Credit: Scientific American)
Dogs, But Not Wolves, Use Humans As Tools (Photo Credit: Scientific American)

Dogs, (Canis lupus familiaris) are descendants of wolves (Canis lupus). What does that mean? Long ago, perhaps about fifteen to thirty thousand years ago, wolves were incorporated into human civilization. How this came to be still remains unclear. However, what is clear is that over that span, the appearance, personality, and cognitive and physical abilities have been altered significantly. Although your typical dog may not be able to take down a moose, it has traded in its physical abilities for a new set of skills, human social skills.

The key factor here is domestication. Living among humans does not necessitate domestication. It can be purely experiential, in which case, is called habituation. When alteration of the genetic code is involved, it is then called domestication. We say dogs are domesticated animals. Does that mean dogs are genetically predisposed to have the ability to socially communicate with humans? Does this mean wolves raised in a human social environment will not have the same communication abilities as dogs?

Scientists at Eotvos University in Budapest wondered those exact questions and designed two experiments in which the social ability of dogs and wolves would be tested. Four to six day old wolf pups and dog puppies were assigned to be raised by humans in very similar experiences, both spending most of the day and night with their human caregiver. In the first experiment, five week-old puppies, nine week-old puppies, and nine week-old wolf pups were tested by a simple experiment. The objective was for the animal to get food from an inaccessible plate which would require human assistance. All the animal had to do was simply make eye contact with their human, and they would be rewarded with food from the plate. By the second minute of unsuccessfully trying to get the food, dog puppies began to look to their human for help. By the fourth minute, dogs had already established the key to getting the food while the wolves still attempted to reach the food on their own.  At the end of the experiment, wolves still failed to realize that eye contact was the key to unlocking the food.


In the second experiment, dogs and wolves were presented with a task of retrieving food by pulling a rope with food tied to the end to reach the food. After mastering the task, both were presented with a rigged version of the experiment in which it was impossible for them to obtain the food. Dogs looked back at their caregiver for help and wolves did not. This concludes that although wolves were fully socialized, they still treated the situation as a physical obstacle. These experiments show that dogs’ social ability to communicate with humans is a direct result from domestication.

Bacteria Mediate Communication Between Hyenas

By Bio 94 Student Ava Pournejad

Mammalian evolution has occurred hand in hand with microbes. It is known that microbes outnumber human cells in our bodies. Along with aiding in digestion, microbes are also required for social communication among animals. A study conducted by Theis et al at the Michigan State University showed that bacterial species present in the scent glands of hyenas are responsible for their social behavior, including mating, same and different species recognition and territorialism. The results obtained by the authors confirmed the fermentation hypothesis of chemical recognition. According to this hypothesis, which was introduced over 30 years ago, microbial species exist in the scent glands of mammals and their aromatic by-products provide the characteristic odor to animal scent. In addition, the microbial species present in the scent of one species or social group differ significantly from other species or groups (Theis et al, 2012).

Spotted and striped hyenas leave messages in smelly trails for other hyenas -- and they're aided by microbes in their scent glands (Dai Kurokawa / EPA / November 11, 2013)
Spotted and striped hyenas leave messages in smelly trails for other hyenas — and they’re aided by microbes in their scent glands (Dai Kurokawa / EPA / November 11, 2013)

Hyenas usually live in large groups or ‘clans’ within which subgroups form, intermingle and dissolve every day. For the purposes of communicating with each other and within each subgroup; for protecting the clan from other hyenas and larger animals and for mating purposes, these mammals employ a large number of specific social behaviors. One of the most common is the act of ‘pasting’, which refers to the rubbing of the secretion of their scent glands onto plants or other surrounding fixtures to mark a scent trail (Theis et al, 2012). The ‘paste’ is a lipid rich compound and contains large numbers of microbes. The paste is the byproduct of fermentation that happens in these microbial species.

The authors collected paste samples from four hyena clans living in the Masai Mara National Reserve, Kenya (Southern Comfort, Fig Tree, Mara River and Emarti Hill). Animals sampled included males, females, pregnant females and lactating females. Paste samples were collected directly from the anal scent pouches of these animals following tranquilization. They were then analyzed by scanning electron microscopy that showed the presence of lipid droplets and rod shaped bacterial cells. The bacterial species were indentified and it was found that along with 78 established genera, there were a significant number of cells that could not be identified with confidence, suggesting the presence of as yet unidentified species.

The bacterial species identified showed a great degree of overlap between members of the same clan. The overlap in microbial species could be from sharing the same plant or object for pasting. This also has the added effect of generating more intense scent trails for better communication, especially for marking territories (Theis et al, 2012). In addition, the type of species that were present on males was different from females. Even among females, lactating mothers had a different subset of bacteria unique to their scent. In this study, spotted hyenas belonging to one clan showed 54 species unique to lactating females and 46 to pregnant females. Species identification and comparison was done by high-throughput sequencing of their 16s RNA.

The findings present in this study suggest the credibility of the fermentation hypothesis of chemical recognition. In addition, it can be assumed that hyenas are not the only mammalian species benefitting from such a relationship with bacteria. Further studies that aim to grow some of these identified bacterial species from paste in a lab setting and show the generation of paste components by these microbes is needed as a validation of these results.

Darwin’s Frogs Decline

By Bio 94 Student Melody Sayrany

Charles Darwin embarked on a journey on the HMS Beagle in 1831 whereby he came to discover numerous species, one of which were the rhinodermatid frogs, also known as Darwin’s frogs, which are native to Chile and Argentina. These frogs are unique in that they can camouflage to look like a leaf to avoid being eaten. They are mainly a diurnal species, but they exhibit mating calls during both night and day where the males court the female then give rapid “pip” sounding calls. The rhinodermatids exhibit a very clever strategy to avoid predators. When threatened, the immediately play dead, lying on their backs, and if near a stream they hop in and float away.

Rhinoderma darwinii looking like a leaf (Source: Wiki Commons)
Rhinoderma darwinii looking like a leaf (Source: Wiki Commons)

In recent discoveries it has been noticed that a skin infection caused by a fungus, known as Batrachochytrium dendrobatidis or Bd, has spread and is killing countless amphibians. By DNA examination of over a hundred preserved amphibian species from the years between 1835 through 1989, it was proven that amphibian chitridiomycosis is causing mortality by causing morphological damage. Such damage includes convulsion of limbs, a medical condition resulting in rapid and repeated contraction and relaxation of muscles causing involuntary shaking, and reddening of skin. Lethargy, lack of energy, and failure to seek shelter and protect oneself as other normal frogs would do is also associated with the disease. The two most affected species of frogs are the now extinct Rhinoderma rufum and endangered Rhinoderma darwinii. Scientists believe the death and decline of these frogs are related to Bd skin disease, however they cannot conclude this relationship for sure for habitat destruction is also a major influencing factor. Some may ask, well why is amphibian extinction such a tremendous deal when so many other animals are also extinct? Well the answer to that would be that these species serve an immense purpose in sustaining ecological balance in the environment. Without them humans would be exposed to diseases carried by plagued insects, for there are no longer any frogs that prey on them, and this would result in an increase in the rise of diseased humans as well as damaged agriculture.

The Fascinating Sex Lives of Sea Slugs

by Bio 94 Student Carrie Meena

In a recent article from Science News, Susan Milius explain a simultaneous forehead piercing that has recently been noticed in a newly discovered sea slug species that has yet to be named. The new species is found in the Great Barrier Reef in Australia and are characterized by their bright yellow, red and white bodies. Another characteristic of the hermaphroditic sea slug is a double set of penile organs. When mating occurs, each sea slug will interwhine around each other and stick out a penis. One penile organ delivers sperm to another slug’s body while receiving sperm simultaneously. The other sharp penile organ then dives into the forehead area of the slug while receiving the sperm. The organ will stay injected in the slug’s forehead for roughly forty minutes or until sperm transfer is completed.

Simultaneous forehead piercing in two tiny hermaphroditic sea slugs © JOHANNA WERMINGHAUSEN
Simultaneous forehead piercing in two tiny hermaphroditic sea slugs © JOHANNA WERMINGHAUSEN

Researchers are still unclear as to why this occurs but the fact that the sea slug does not try and avoid the second penile organ implies that no harm is happening. Comparisons to other species suggest that the sea slug might be possibly slipping manipulative compounds into their partner such as a biochemical that will make it harder for that sea slug to accept sperm from the next mate. This type of transfer is apparently extremely common among hermaphroditic animals according to evolutionary biologist Menno Schilthuizen of Leiden University in the Netherlands.

The News According to Bio 94 Students

The Truth About Nemo: How He Helps His Anemone Host Breathe

By Bio 94 Student Tanya Tatavets

When the Walt Disney movie Finding Nemo came out in 2003, Nemo, the little clownfish, stole the hearts of viewers. During one scene the teacher asks Nemo “you live in what kind of home?” he replies “an Amnemonemomne”, trying to pronounce the animal’s name. Nemo would swim back and forth through the anemone seeking protection.  Many may not realize that anemone not only provide shelter for clownfish, but clownfish also play a vital role in the survival of the anemone. They share a symbiotic relationship, or a relationship with mutual benefits. Clownfish are immune to stings from anemone while many other predators are not. In addition, the clownfish will “chase away any polyp-eating sunfish eyeing the anemone’s tentacles for a meal” (Polyps are animals that are sedentary and attached to a substrate).

Clownfish taking shelter in an anemone. Photo by: Joseph Szczebak
Clownfish taking shelter in an anemone. Photo by: Joseph Szczebak

All the swimming that Nemo was doing not only served as protection, but it helped to “oxygenate the anemone at night, when oxygen levels in the water are low.” Anemones aren’t capable of regulating the water flow over their tissues. This results in low oxygen conditions, but clownfish help to provide a supply of oxygen-rich water.

In an experiment conducted by Joseph Szczebak, lead author of the paper in the Journal of Experimental Biology, and his colleagues from Auburn University, the “nocturnal behavior of the clownfish-also known as the anemonefish” was observed. They studied the interaction of the anemone and clownfish in four different ways: when the clownfish was with the anemone, when they were away from each other in two separate containers, and two styles of variation where the clownfish and the anemone were in the same container but separated by a net. The first variation with the net separation is with the clownfish above the anemone so that the water flow passes the clownfish before the anemone and the second variation is with the anemone above the clownfish.

From Szczebak et al: ‘Flow-through respirometry treatments to assess the effects of symbiotic interactions on the dark oxygen uptake (VO2) of two-band anemonefish (A. bicinctus) and bulb-tentacle sea anemones (E. quadricolor). Mesh subtreatments, mesh1 (1) and mesh2 (2), are depicted. Respirometry chambers were constructed from 6.35-mm-thick acrylic cylinders (inner diameter, 16.5 cm) with a volume of either 2.5 or 3.5 l (depending on animal sizes).’

The reason for the net was to study if sight or smell had anything to do with the oxygen uptake or the behavior of the animals. The research ended in the conclusion that although the clownfish seemed to have more movement when it could smell the anemone, it did not result in a considerable increase of oxygen uptake for the anemone. Only when the animals were together, when the clownfish was swimming within the anemone, did the oxygen uptake rise for the animal. The clownfish also showed more rapid movement when the two were placed in a shared container with no netting. When the animals were separated, the clownfish did not show as much movement.

The research done by Szczebak and his colleagues was only a small dent in understanding these types of natural relationships. It is hopeful that the study will allow for deeper insight and research on the symbiotic relationship between anemones and clownfish. Read more here!

Girls Rule! (Or At Least For the Painted Turtles)

by Bio 94 Student Michelle Green

Painted turtles (Chrysemys picta) are found in lakes and streams of North America and are one of the many reptile species where sex is determined by temperature of their environment.  The exact reason is unknown as to why temperature can have an effect on reptile eggs, but we do know that cooler temperatures are more likely to hatch males, while warmer temperatures are more likely to hatch females.  As Global warming continues, the fact that rising temperature could increasingly result in a complete female dominate population is a major concern to biologists because it would lead to the extinction of the entire population.

Painted turtles set to become all female (Image: Lorin Neuman-Lee)
Painted turtles set to become all female (Image: Lorin Neuman-Lee)

For over 25 years, Fredric Janzen at Iowa State University has been documenting the nesting times and sex ratio of painted turtle generations on a small island in the Mississippi River in Carroll County, Illinois.  He discovered that females can actually shift their nesting dates by about 10 days to make sure that the sex ratio would be even amongst males and females.  These studies led to further studies, at the Iowa State University, led by Rory Telemeco and his colleagues.

Telemeco and his colleagues used Janzen’s findings and historical records of soil and air temperatures to develop a mathematical model that can predict the sex ratios of Painted Turtle hatchlings at a specific temperature.  In a preliminary test of the model, Telemeco’s team predicted the sexes, of Painted Turtle hatchlings, 87% correctly.  The group then used the mathematical model to predict future sex ratios of the populations, with the change in future temperature changes.

Telemeco’s team discovered that the temperature would only need to rise by 1.1°C for a completely female dominated population. According to some climate models, the average temperature in the United States’ Midwest is supposed to rise 4°C over the next 100 years.  This would consequence in all female egg hatchlings which would ultimately lead to the extinction of Painted turtles.

Some evolutionary biologists such as Richard Shine, an evolutionary biologist at the University of Sydney in Australia, who was not tangled in the study, is positive about the turtles chance of overcoming this change through adaptations such as gaining the ability to handle warmer conditions or by learning to lay their eggs in a more conducive area to an equal sex ratio, such as a shady, cooler location.

Although Shine remains positive on the subject, Telemeco isn’t so optimistic.  Telemeco feels that the climate change is occurring so fast that there would not be adequate time for an evolutionary change to occur in the Painted Turtles.  Last month, April 2013, the turtles’ complete genome was sequenced.  The genome could give us clues on how the genes may respond to climate changes.

Hopefully, the turtles will be able to adapt to the temperature changes or the entire population will become females, leading to the extinction of this species.  Shine also states that “all crocodilians, a smattering of turtles and lizards, plus some fishes” will be affected.  This is of great concern because if one piece of the ecological puzzle is missing, it could cause a chain reaction and affect other species as well.

Amphibians Living Close to Farms Are More Resistant to Common Insecticides

By Bio 94 Student Asheesh Patel

According to recent studies at the University of Pittsburg, amphibian populations that live near agricultural fields have developed some resistance to certain insecticides. The study, which was published in Evolutionary Applications reveals that tadpoles that live near farm fields are resistant to the insecticide, chlorpyrifos. Chlorpyrifos which is also known by Dursban or Lorsban, is an organophosphate insecticide  used to control foliage and soil-borne insect pests on food crops. Over ten million pounds of  chlorpyrifos is used annually by farmers in agricultural settings.

Wood frogs living close to agricultural land were more likely to have been exposed to pesticides for many generations compared to those living far from agriculture. (Credit: Image courtesy of University of Pittsburgh)
Wood frogs living close to agricultural land were more likely to have been exposed to pesticides for many generations compared to those living far from agriculture. (Credit: Image courtesy of University of Pittsburgh)


Study principal investigator Rick Relyea, Pitt professor of biological sciences and director of the University’s Pymatuning Laboratory of Ecology, explained  “Our study is the first to explore how amphibian populations might evolve to be resistant to insecticides when they live in places that have been sprayed for many years.” To conduct the study, a group of Pitt researchers collected tadpoles from nine different wood frog populations at varying distances from agriculture and tested each frog’s resistance to chlorpyrifos and Roundup Original MAX®, a herbicide to stop weeds from growing. The tadpoles were set in environments with either no pesticides, chlorpyrifos, or Roundup® for 48 hours to see how resistant the tadpoles were.

Rickey Cothran, the lead author of the study, revealed that wood frog populations closer to fields were not more resistant to Roundup®. Jenise Brown, a coauthor of the study and a former undergraduate researcher in Relyea’s lab, believed that the resistance to chlorpyrifos developed because many insecticides kill organisms the same way chlorpyrifos does. By spraying one insecticide, the frog populations developed resistances to other insecticides. However, herbicides kill organisms in different ways so it is more difficult for an organism to become resistant to a herbicide. To test this, the group used three commonly applied pesticides with  similar chemical properties — chlorpyrifos, carbaryl, and malathion. The group exposed 15 populations of wood frog tadpoles to each insecticide and  found that wood frog populations with resistance to one insecticide also had resistance to the other insecticides. The researchers concluded that cross-resistance may result from that fact that insecticides kill in similar ways so that resistance for one insecticide will increase resistance to others.

In the future, the researchers plan to study the genetic mechanisms that underlie increased resistance to insecticides in amphibians and whether other animal species have already developed similar resistances to insecticides.

Bloomin’ in the OC

Great weekend to take advantage of the nice weather and get out to find some blooms! I am hoping that more rain will bring more blooms and that we can expect a spectacular wildflower season. Here in Orange County, the landscape is turning green and we are already seeing some early blooms. Last weekend, I joined the California Native Plant Society for a stroll through El Moro Canyon in Crystal Cove State Park. Here are a few of the gems…


Female (above) and male (below) catkins of Arroyo Willow (Salix lasiolepsis).  

We have several species of willows in our area and these riparian plants are rarely found far from surface water. Salicylic acid, a precursor of aspirin, is present in European willows but our local willows don’t seen to be suitable for similar extraction. Willow identification can be tricky, and the occasional hybrid exacerbates the problem. Salix lasiolepsis is the most common willow species here in Southern California. Whereas other willow species have finely tapered leaf tips, the leaves of arroyo willow are broad throughout, all the way to the tip. The upper surface of arroyo willow leaves are a bright green and contrast with the bluish-grayish underside.  Willows are dioecious – having male and female flowers on entirely separate plants.



Lathyrus vestitus – Chaparral Sweet Pea. 

This member of the Fabaceae can be easily recognized by its classic pea family flowers: the conspicuous uppermost petal, the banner, the two side petals, the wings, and the two fused lower petals, the keel. The keel is hinged and the weight of a pollinator quickly exposes the stamens, depositing pollen on the underbelly on an insect while simultaneously introducing pollen from a previously visited flower to a fresh stigma. The chaparral sweet pea looks quite similar to the garden sweet pea (Pisum sativum) and the flowers are pretty much indistinct….you have to look at the stems and petioles to distinguish these two. Pisum stems and petioles are round and Lathyrus are winged with ridges that run longitudinal.


Cardamine californica – California Toothwort or Milkmaids

This member of the Brassicaceae is one of our earliest spring flowers. Its common name refers to the bulges, or “teeth” on its roots. It earned its species name due to some supposed medicinal value – Cardamine means “I strengthen the heart”


Asterella sp. – Liverwort

No vascular tissue, no seeds, no flowers….no problem. This seedless, nonvascular plant reproduces by means of spores. Without a vascular system to transport water around its body, it is typically restricted to moist environment and grows in close contact with the moist soil. Both the gametophyte and sporophyte are visible in the picture above.


Ribes speciosum – Fuchsia-Flowered Gooseberry

This spectacular evergreen shrub typically begins blooming in February and is already being quite the show off! Its bristly branches are lined with an abundance of drooping, showy, bright red flowers that are 1/2″ or more long. This plant typically occurs in shady canyons and lower elevations, mostly near the coast.






Marah macrocarpus – Wild Cucumber

This vine is quite common in sage scrub and chaparral and can be found now bearing both fruits and flowers. Small white flowers appear in early spring (look for the separate male and female flowers on the same plant – female flowers are near the base and are easily recognized by their fat ovaries). The resulting fruit, shown above, is a prickly gourd. These soft, green prickles will turn hard and spiny as the fruit dries, eventually opening to reveal 4 chambers filled with black seeds.

Quercus-lobata-Jan13And drumroll please…………..the southernmost Valley Oak (Quercus lobata) in the WORLD!!! Well, what is left of it anyway after a fire.

Also seen along the trail but not pictured here: Acmispon glaber, Mimulus aurantiacus, Rhus integrifolia, Encelia californica, Artemisia californica, Cleome isomeris, Opuntia sp., Malosma laurina, Malacothamnus fasciculatus, Symphoricarpos mollis, and more!

Noteworthy Species of 2012: Orchids working the night shift and Spongebob mushrooms

It is that time of the year again! Best of this, best of that. This top ten list won’t appear on the cover of People Magazine, but is far more fascinating than any other you may come across! 2011 is the 5th year that the International Institute for Species Exploration at ASU presented its list of the Top 10 New Species. Over 18,000 new species were described in 2011, and these are just a few of the most noteworthy. First up….plants and shrooms!

An Orchid on the Night Shift

I am thrilled that two new plant species made the list! The first, Bulbophyllum nocturnum, is a species of orchid that opens its flowers at night. This might not seem all that shocking – many species of flowering plants take the night shift to attract pollinators such as moths and bats who are most active at night. And, of course, the orchid family is renowned for having evolved a myriad of tricks to attract its pollinators. But of the 25,000 known species of orchids, this is the first that exclusively blooms at night – and for one night only, attracting nocturnal flies looking for a place to deposit eggs. This new species was discovered in a logging area of New Britain, and researchers are calling on Papua New Guinea’s to protect this habitat.

Night-blooming orchid, Bulbophyllum nocturnum

How did this stunner go unnoticed?

It is amazing to think about how such a dramatic bloom could go unknown until now. Well, I guess its not that shocking when you take into account where this beautiful and vibrant poppy, Meconopsis autumnalis, lives – in central Nepal at elevations between 10,827 and 13,780 feet. This plant has been collected twice before – in 1962 and 1994 – but was not recognized as new at that time.

Nepalese Autumn Poppy, Meconopsis autumnalis Photo: Wikipedia

Spongebob Squarepants is….a mushroom??

Photo credit: Thomas Bruns, Interior (left) and exterior (right) views of Spongiforma squarepantsii; center: Dennis E. Desjardin & Andrew Ichimura, SEM photograph of spores of Spongiforma squarepantsii
Photo credit: Thomas Bruns, Interior (left) and exterior (right) views of Spongiforma squarepantsii; center: Dennis E. Desjardin & Andrew Ichimura, SEM photograph of spores of Spongiforma squarepantsii

Do you see the resemblance?  This newly discovered species of fungus is named after the cartoon character Spongebob Squarepants! Why? Well, this new species looks more like a sponge than your typical mushroom and its fruiting body can be squeezed like a sponge and bounce back to its normal size and shape. The species discoverers’ argue that its more than this physical similarity that earns this fungus its name, “the mushrooms smells fruity and Spongebob lives in a pineapple; magnified, the texture of the fungus resembles the tube sponges covering the seafloor where Spongebob lives; and even the microscopic spores of the fungus appear spongelike. Although the species name was initially rejected by journal editors as “frivolous,” the authors persisted and as a result, brought attention to a bizarre new species and to the biodiversity of the world’s forests.” Read more about this discovery at Science Daily.

Up next…..worms, and jellies, and bugs, of 2011……!!

Animals Poised to Take Over the World – Zombie Parasites and Tool-Using Cockatoos

How Zombie Parasites Are Taking Over the World – by Bio 94 student Kiana Daraee

Recent studies in parasitology are examining how a parasite takes over it’s host and manipulates it’s behavior.

One way a parasite can change another organisms behavior is by introducing a new gene or altering an existing gene found in the host. An example is the virus baculovirus that contains the gene egt which codes for an enzyme that interferes with the hormone that tells a caterpillar when to stop eating and molt. When a caterpillars eats a leaf coated by baculovirus it goes into a “feeding frenzy.” Normally a caterpillar only comes out at night to search for food but an infected caterpillar continues to climb higher up a tree and search for food. Similar to the zombie ants we learned about in class when the zombie caterpillar reaches a treetop it dissolves spreading the virus over a large area.

In Costa Rica there is a parasitic wasp that needs to infect a spider, Anelosimus octavius, in order to survive. The infected spider leaves its own web and spins a new one that is different from its original web and better suited for the wasp. After the new web has been spun the host spider dies the parasitic wasp’s larva emerges continuing its life cycle, building a cocoon, under the shelter provided by the new web.

When infected by thorny-headed worms (the orange spot), gammarids swim toward light. At the water’s surface they become easy prey for birds, the next creature the worm needs to infect to complete its life cycle. Credit: NY Times

Other parasites interfere with neurotransmitters in the host’s brain. The thorny-headed worm is a parasite that needs to pass through two different species to survive, like the trematode. Its first host is a crustacean called the gammarid that lives in dark and muddy areas of a pond. Once a gammarid is infected by a thorny-headed worm it produces an excess of the neurotransmitter serotonin that can alter visson. This causes the gammarid to see the light on the water’s surface as being darker and the gammarid will swim towards the water suface instead of hiding in deeper and darker waters. The gammarid is then easily spotted and eaten by a preying bird who also ingests the thorny-headed worm enabling it to continue it’s life cycle.

The single-celled parasite, Toxoplasma gondii, also needs two hosts to survive. First it is picked up by a mammal or a bird, then the new host is ingested by a cat where the parasite can reproduce in the cat’s intestine and latter be shed. Toxoplasma produces an enzyme that leads to an increase of the neurotransmitter dopamine causing them to be less fearful and less cautious when then pick up a predators scent. Toxoplasma gondii is one of the known “vertebrate zombies” that can infect a human and has been linked to personality changes and schizophrenia.

The wacky life cycle of Toxoplasma gondii. The only definitive hosts are members of the Family Felidae (domestic cats and their relatives). Humans may become infected by eating undercooked meat harboring cysts, consuming fecal-contaminated food or water, through a blood transfusion, or from mother to fetus. Credit: CDC
The wacky life cycle of Toxoplasma gondii. The only definitive hosts are members of the Family Felidae (domestic cats and their relatives). Humans may become infected by eating undercooked meat harboring cysts, consuming fecal-contaminated food or water, through a blood transfusion, or from mother to fetus. Credit: CDC

By studying known parasites some believe that they could help pharmaceutical companies create new drugs that could help control the symptoms associated with mental disorders. Read more at NY Times.

Cockatoos use tools too – By Bio 94 Student Lauren Nguyen

Researchers were recently surprised by a  cockatoo was discovered to be able to make and use tools in order to obtain food. This is not known to happen in the wild. The only birds that are known to make tools are birds that belong in the corvid family. Tool-making is very rare in other birds. The study was first published in the journal Current Biology. It was conducted near Vienna, Austria by scientists from the University of Oxford, the University of Vienna, and the Max-Planck-Institute for Ornithology.

Researchers first made the discovery when Figaro was playing with a pebble. He dropped it outside of his cage and attempted to reach the pebble with his claw. After he realized that his strategy wasn’t working, he fetched a stick and poked it through the cage so that he could retrieve his pebble. The researchers were so fascinated by this that they conducted further experiments.


The researchers placed a nut outside of Figaro’s cage. Figaro got a stick and tried to reach for the nut. However, this was unsuccessful.  He then found a wooden plank and bit splinters off of it. When the splinter was the right size and shape, he used them to rake in the nut. They repeated this experiment with Figaro ten times over the course of three days. Each time the researchers conducted this experiment, Figaro was successful in obtaining his food. They also found that the more time they did this, the more efficient Figaro became at reaching his food. He became faster at biting off the splinters so that they were the perfect size and shape. It was as if Figaro applied the knowledge and skills he learned from previous experiments.

This is the first recorded instance in which a parrot makes and uses a tool. Professor Alex Kacelnik of Oxford University states that “No one has ever reported [a parrot] sculpturing a tool out of shapeless wood in order to use it later with greater sophistication.” Although Figaro is the only known parrot to have displayed this skill, this discovery can provide new insight on the intelligence of the species. Read more and see a video of Figaro at BBC Nature. Or read about some of nature’s other tool makers and users:


My students have heard my warning about potential suitors trying to kiss them beneath Mistletoe during the Christmas season. This plant which is meant to symbolize love and peace is actually a parasite that penetrates its’ host vascular system to steal away much needed water and nutrients!!  How does it get into a tree’s canopy to become a freeloader? Well, birds eat the juicy berries (shown below) and the seeds pass out with their poop and stick to whatever branch they happen to land on, where the seeds will germinate and the mistletoe will parasitize a new host!

European Mistletoe, Viscum album, is the “original” mistletoe, although the term refers to a group of hemi-parasitic plants all in the order Santalales. The berries shown above are dispersed in bird poop.

But apparently Mistletoe isn’t the only Christmas parasite — figgy pudding, reindeer, even turtle doves also have to deal…

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