Friday, March 30, 2012

Alpheid Shrimp/Gobbid – The Landlord and his Tennant


Introduction: The Alpheid shrimp its Gobbid (the goby), engage in a very interesting mutualistic relationship.  While the shrimp burrows in the sand digging a home for the two, the goby keeps an eye out for predators and any sign of danger.  Goby-Shrimp relationships can be found in numerous tropical regions but extensive research has been done in the Red Sea, Japan, and Hawaii.  Over 70 different species of gobies have been associated with shrimp so far [1].  Specific shrimp goby partnerships often change.  When researchers tagged the shrimp and the gobies, often times individual shrimp goby pairs split up and found new partners [1].

Description of the Relationship:  Many researchers have tried to figure out how the shrimp/goby relationship has formed.  Most have come to the conclusion that the relationship evolved as a way for both species to avoid predation [1].  Many Alpheid shrimp are nearly blind, so without their goby partner, they are unable to detect predation [2].  The two find each other in different ways.  The goby relies on vision to find its shrimp partner, where as the shrimp relies on chemical attractions to the goby[1].  While the shrimp digs through the sand, the goby hangs out behind him looking out for danger.  Because the shrimp is nearly blind, he keeps one antenna on the tail of the goby at all times [1].   When the goby detects danger, he slightly flicks his tail, which signals the shrimp to dart into its burrow, with the goby following behind [1].  Because the partnership helps reduce encounters with predators and it does not involve any metabolic processes, this type of mutualism would be considered facultative.  Each, individual could live without the other, but when, paired together, it decreases death caused by predators.

Cost/Benefit Analysis:  There is a fairly even ratio of cost to benefit in the shrimp/goby interaction.  While the shrimp uses a lot of energy to burrow in the sand, he greatly benefits from the protection of the goby because without the goby, the shrimp could not see its predators and would be easy prey.  Although the goby acts as a look out for the shrimp, he gets in return a place to hide from predators.  The shrimp always keeps his antenna in contact with the goby as to not lose his partner.  The shrimp puts more effort into this relationship but also arguably has more to lose without it.


Thursday, March 29, 2012

Cactus Wren on Cholla: Best Buddies

Cactus Wren on Cholla: Best Buddies

The Cactus Wren, also known as  Campylorhynchus brunneicapillus, is the largest bird found in parts of North America such as Southern California, Southern Nevada, Arizona, New Mexico, Utah, Western Texas, and Northern Mexico [1]. The normal size of a wren is about 8 inches long [1]. Campylorhynchus brunneicapillus is distinguished from other birds because it's belly has spots, and speckled brown, black and white feathers on its back, wings and head. It also has black feathers on its throat and a long stripe of white feathers [1]. Campylorhynchus brunneicapillus lives in desert areas such as a large cactus known as Cylindropuntia, commonly known as 'cholla' [2]. Campylorhynchus brunneicapillus  finds its food from the ground using its long bill. They usually eat ants, beetles, grasshoppers, wasps, fruits and seeds. However, it also eats small frogs and lizards. The wren is adapted to the life in the desert and gets most of the water from the food it eats in order to survive [1]. Cylindropuntia  are found in North American deserts with more than 20 species found in the Southern America [3]. "Cholla" is the term used to describe shrubby cacti with cylindrical stems that have segmented joints [3].  The cactus wren lives on large cacti like the 'cholla' in order for the cholla to hold its large nests.There is a commensalistic relationship between the cholla cactus and wren.

Commensalism is a relationship in which one of the organism's benefits (gets what it needs) while the other organism neither benefits nor is harmed. In the relationship between the cactus wren and cholla, the cactus wrens build their nests in cholla cacti. The spines of the cactus help by protecting the nest from predators. In this relationship, the cactus wren receives what it needs, i.e. nest protection [4]. The cholla cactus neither benefits nor is harmed by the nests that the cactus wrens form [4].

Cost/Benefit Analysis:
There is no cost in this relationship for the cactus wren. The wren benefits from the cholla by gaining shelter without harming the cholla. The wren builds its nest inside the cholla so that it has a cooler place to live in rather than the hot weather outside in the desert. The cholla also helps the wren by protecting it from predators through its spines. The cholla has no cost because the wren does not harm the cholla in any way. The cholla helps the wren by providing it shelter.


Wednesday, March 28, 2012

The Anglerfish and Her Pyrotechnic Display:


The anglerfish is a large group of more than two hundred species of deep sea-dwelling fishes of the order Lophiiforms. Anglerfish are generally less than a foot long, but may reach lengths of up to 3.3 meters [1]. They appear dark gray to dark brown with enormous heads that are loaded will numerous sharp, invisible teeth. One of the most interesting features of the anglerfish is its method of reproduction. The male anglerfish is much smaller than the female and when it encounters a mate, the male anglerfish fastens on by means of its mouth [1]. Gradually, the male is absorbed by the female until the only organ remaining is the testes. This ensures that when the female anglerfish releases her eggs, she will have a ready supply of sperm [1].
These unique fishes are found in the Atlantic and Antarctic oceans in the bathypelagic zone which extends from 1,000 to 4,000 meters below the ocean’s surface [2]. The problem that most organisms face at this depth is the limited amount of sunlight that is capable of reaching this layer. Inevitably, this makes capturing prey and avoiding predation a very daunting task. However, Lophius piscatorius is a model species of this large group of anglerfish which utilizes a long, bioluminescent rod that extends from above its mouth found only on the females [1]. This rod, which is actually an extension of a dorsal spine, is home to a colony of bioluminescent bacteria that enable L. piscatorius to easily lure curious prey towards its plethora of razor teeth [3].
Description of the Relationship:
                The relationship between the anglerfish and its bioluminescent bacteria can most clearly be defined as mutualism in which both partners benefit from the relationship. The presence of the internal mutualist bacteria allows the host anglerfish to capture prey more easily, while the so-called fishing rod that houses the bacteria provides a nutrient-rich environment for the bacteria to flourish [4]. Presumably, this organ has openings to the ocean that allows the bacteria to colonize and form a very specific relationship. For example, while it is still unknown which bacteria colonize the specialized dorsal fin of the anglerfish, other relationships between bioluminescent bacteria and deep sea fishes suggest that only one bacterial species is involved [4]. Genetic data provided by Haygood (1993) suggests that the bioluminescent bacteria are most likely from the genus Vibrio which produces bioluminescence through quorum sensing [5].  
                Quorum sensing functions to produce bioluminescence in many bacterial colonies by manufacturing the necessary cellular products to generate luminescence only after a particular threshold of bacteria has been established in the colony [3]. Bacteria produce molecules that are released into the environment and by sensing the number of these molecules, they can accurately estimate how many bacterial cells are present.  Once that critical number of bacteria is present, the colony of bacteria begins to glow.
                The light organ that houses these bacteria in the anglerfish constantly leaks bacterial cells into the surrounding ocean at a rate of about 107 to 108 cells per hour from colonies of about 1011 cells per milliliter [4]. By leaking these bacterial cells into the surrounding water, the progeny of the anglerfish are able to develop lures with the same bacteria as that of their parents through vertical transmission as well as providing an environmental reservoir [4].
                The relationship between bioluminescent bacteria and fishes is not unique. In fact, there are several examples that include deep sea spookfish and rattails employing Photobacterium phosphoreum and, in shallower water, flashlight fish and pony fish utilizing Vibro fischeri or Photobacterium leiognathi [4].  As mentioned earlier, the bacteria that live inside the rod of the female anglerfish are most likely from the genus Vibrio [5]. Bacteria from the genus Vibrio are more closely associated with those that emit bioluminescence in the gut of the fishes, such as in the shallow water pony fish, rather than other deep sea fishes which house their bioluminescent bacteria in specialized compartments [6]. Therefore, this discovery suggests that the mutualism between the anglerfish and these particular bioluminescent bacteria is, evolutionarily, a newly formed relationship.
Cost/Benefit Analysis:
                For the anglerfish, participation in such a relationship with its bioluminescent partner seems rather easy. For the minimal resources that it must supply to the colony of bacteria, it significantly increases its chances of capturing prey by mimicking fecal matter—a source of food to bathypelagic organisms which also glows as it falls downward—drifting from the upper layers of the ocean [7].  This does require some maintenance on the part of the anglerfish, however. The anglerfish must: maintain the population of bacteria while removing excess bacteria or dead colonies, ensure that the bacteria stays only in the lure, be able to switch the bioluminescence on and off, and somehow guarantee that the same bacterial colony is passed on to its offspring [4]. All of these housekeeping procedures come with an energetic cost to the organism. Another cost to the anglerfish may be even more obvious: by increasing its own visibility, it also increases the chances that it will be seen, and consumed, by larger predators than itself.
                On the other hand, by participating in the mutualisitic relationship, the bacteria are promised a constant supply of nutrients and a relatively constant environment to thrive. However, by remaining inside the lure of a single host over time, evolution limits its ability to form free-living marine colonies and the bacteria are permanently linked to its host organism [4]. There are also energetic constraints involved with producing bioluminescence; however, these are generally small and only about 0.01% of the cells expenditure is utilized by bioluminescence [4]. Lastly, by increasing the anglerfish’s chances of being consumed, it decreases its own reproductive fitness. If the host anglerfish is eaten by an unsuitable host, the bacteria are lost to the gut of the predation. However, if the bacteria are able to survive in the gastrointestinal tract of the predator, the bacteria released with the feces may help the bacteria to move to a new suitable host anglerfish—thus, allowing the cycle to continue.


The above video shows the bacterial bioluminescence of the anglerfish in action as well as gives some other examples of deep sea organisms that utilize similar methods of bioluminescence.


[1] “Anglerfish.” National Geographic. Web. 25 March. 2012.
[2] “The Bathypelagic Zone.” OceanLink. Web. 25 March. 2012. 
[3] Naik, G. “Deep Inside Bacteria, a Germ of Human Personality.” The Wall Street Journal
          Web. 26   March 2012. <>.
[4] Herring, P. “Marine microlights: the luminous marine bacteria.” Microbiology Today 29 (2002): 
          174-176. Web. 26 March 2012. <>.
[5] Haygood, M. “Light organ symbioses in fishes.” Crit Rev Microbiol 19 (1993): 191-216. Web. 
[6] Dunlap, P. V. and K. Kita-Tsukamoto. “Luminous bacteria.” Prokaryotes 2 (2006): 863-892. Web. 
          27 March 2012. 
[7] Latz, M. I. “”Biological Light in the Ocean Darkness.” Scripps Institute of Oceanography. Web. 
          27 March 2012. <>

Tuesday, March 27, 2012

Foraminifera and Algae- Be my chef

            Foraminifera is a class of amoeboid protists that are distinguished by their psuedopodia and their tests (shells).  They are found all over the world in estuaries and marine habitats. Forams can be classified as benthic or planktonic based on whether they are found floating on the water’s surface or on the ocean floor. The tests of forams often accumulate on the ocean floor and in coral reefs.[6] Many have been found to date back to the Cambrian period.  The tests of foraminifera contribute to major landmarks such as the Pink Sands of Bermuda, the White Cliffs of Dover, and the stones that make up the Great Pyramids of Egypt. [1,7]
            The tests of Foraminifera are often used by paleontologists to determine past environments, relative ages of marine rocks, water chemistry, and to find petroleum.  In fact, oil industries have started hiring paleontologists who specialize in foraminifera to help direct drilling and increase well productivity. [4]
Many Foraminifera are kleptoplastic in that they have an endosymbiotic relationship with algae. These algae may include green algae, red algae, golden algae, diatoms, and dinoflagellates. The forams sequester the algae for nutrition and the forams provide a home for the algae.  Nitzschia frustulum symbiotica is found in about thirty percent of the associations, and is the most common of the diatom symbionts.[2]
The life cycle of foraminifera varies. The smaller species reproduce only asexually through budding or multiple fission. The larger forams alternate between sexual and asexual phases, between haploid and diploid generations.[6]

The Relationship
            There are two main factors that predispose Foraminifer for symbiosis. The first factor is the compartmentalization of their tests. Foraminifera test structure can vary in chamber arrangement and in the type of apertures they contain.[6]  The chambers of the tests can be subdivided allowing compartmentalization of different cellular activities. This poses as a benefit for the forams because it separates digestion from its symbionts. The second factor that contributes to their ability for symbiosis, is that they reproduce via asexual reproduction. Asexual reproduction insures vertical transmission of symbionts.[3]

            The initial recognition between foraminifera and the potential symbiont is mediated by a cell signaling system involving a specific surface antigen, the common symbiont surface antigen (CSSA). Receptors for CSSA are abundant on the pseudopodia of Forams and make the initial contact with the algae/diatoms. [4] After contact, the diatom is phagocytosed and brought into the interior of the foram’s test, away form the active digestive process.
Because they contain more than on chamber, one host is capable of harboring more than one species of diatoms at a time. The figure below details which algae species grows within certain foraminifera life forms.

            Once the algae are sequestered, the foraminifera use the algae’s ability to photosynthesize to their benefit and acquire the nutrients produced by the algae. During the day, the algae migrate onto the pseudopodia to expose themselves to more sunlight so they are capable of photosynthesis. Then at night, are drawn back into the foraminifera so that the nutrients may be sequestered. In return, the foraminifera provide algae with a home and a place to “farm”.
            There is a hypothesis that suggests that symbiosis may have contributed to the evolution of certain groups of foraminifera tests. There is supporting evidence in fossil records that make researchers believe that the relationship between foraminifer and algae is a long and continuing one. The greenhouse nature of the transparent tests, the canals, and the pores in the test of many larger foraminifera are all thought to be adaptations to symbiosis.                                                                                                           

Cost/Benefit Analysis
            The ultimate benefit of the relationship between Foraminifera and algae are quite simple, the algae provide the food and the forams provide the shelter. An additional, less studied, benefit of this relationship pertains to calcification of foram tests. Calcification of the test is enhanced in the light. Symbiont-bearing forams migrate toward or away form the light sources if conditions permit them.[2] By moving in the light the forams benefit by increased calcification and increased photosynthesis by the algae.
            Some costs that may arise from this relationship include nutrient and habitat limitations for the algae and selectivity for the foraminifera. There are limitations on algae habitat because the algae can only grow within the foram, which may cause there to be limited space. Also, the algae must adjust to the habitat in which that foram is living.  Things such as light ad nutrients sources may not be as abundant as the algae may need. For example, the population density of zooxanthellae on coral, and the foraminifera that inhabit the coral,
is controlled by systematic nitrogen limitations within the host. If there is not enough nitrogen to keep the algae “happy” the zooxanthellae may outgrow their host and the host loses control over the symbiotic algae. [2]
            The foraminifera must be selective in the algae species that it allows to grow in its test.  A number of species of forams cannot grow if they are starved, even when they are incubated in the light. The algal photosynthesis alone does not satisfy their needs. Therefore, there is a cost for the foraminifera and the algae due to selectivity. Foraminifera can only choose algae that will meet their nutrient needs, and algae can only live in foraminifera that will allow them to live there.
( a good example of how Foraminifera "bring in" their symbiont using their pseudopodia)

Works Cited

1. "Foraminifera." UCL. JISC. Web. 10 Feb. 2012. <>.

2. Lee, John J. "Algal Symbiosis in Larger Foraminifera." Symbiosis 42 (2006): 63-75. Print.

3. Lee, John J., and Pamela Hallock. "Algal Symbiosis as the Driving Force in the Evolution of Larger Foraminifera." Annals of the New York Academy of Sciences 503.1 Endocytobiolo (1987): 330-47. Print.

4. Nooijer, L., Toyofuku, T., Kitozako, H. “Foraminifera promote calcification by elevating their intracellular pH.” Proceedings of the National Academy of Science 106.51 (2009):21500-21504

5. Pawlowski, J., M. Holzmann, C. Berney, J. Fahrni, A. J. Gooday, T. Cedhagen, A. Habura, and S. S. Bowser. "The Evolution of Early Foraminifera." Proceedings of the National Academy of Sciences 100.20 (2011): 11494-1498. Print.

6. Wetmore, Karen L. "Introduction to the Foraminifera." UCMP. 14 Aug. 1995. Web. 9 Feb. 2012. <>.

7. "White Cliffs of Dover." - Answers in Genesis. 2012. Web. 21 Feb. 2012. <>.


Sunday, March 25, 2012

Moray Eels and their Maids

            There are over 80 different species of moray eel, including the common “Giant moray”, Gymnothorax javanicus, the “Zebra moray”, Gymnomuraena zebra, and the “Snowflake moray”, Echidna nebulosa. All of these creatures are classified as fish and can typically be found in reefs of tropical and subtropical waters.  They prefer to live in brackish water and use rocks and coral as forms of concealment from both predators and their prey. As carnivores, morays prefer to feed on other fish or cephalopods and usually hunt for such prey at night. [2] Because their eyesight is incredibly poor, eels are known to have an incredibly keen sense of smell that helps them to identify potential food sources, which they then attack using their incredibly powerful jaws. [1]

            Also found in tropical and subtropical waters are cleaner shrimp, especially the "Pacific Cleaner Shrimp", Lysmata amboinesis.  These tiny creatures grow to be up to 6cm long and are omnivores that prefer to eat parasites and dead tissue, especially off of other animals. Because of their incredibly social nature, these shrimp congregate with other cleaner animals and wait for large fish to request their cleaning services.[5]

Description of the Relationship
            Surprisingly, despite a diet high in crustaceans, eels tend to shy away from eating certain shrimp, and particularly cleaner shrimp. While these shrimp would be an excellent source of food to a moray, they are completely neglected and actually invited to swim inside the fish’s mouth without risk. Morays seem to not only realize that the shrimp remove parasites from their bodies, but can also tell if they are doing a thorough job.[3]
            Cleaner shrimp actually do complex dances in the coral reef to demonstrate that they are available to clean, and despite their strong predatory behavior, eels become incredibly docile and allow the shrimp to begin their work. [4] Moray eels can often be observed with one or several of these cleaner shrimp that comb over their bodies, mouth, and even in between their teeth searching for parasites. The shrimp even swim inside the gills of the eel in search of ectoparasites.
The parasites provide the shrimp with nutrition, while the eels are happy to be cleaned and freed of these harmful parasites. Interestingly, eels are covered in a layer of mucus which is actually much more appetizing to the shrimp, yet they have learned to avoid the mucus and strictly eat the parasites. This is because if a moray eel senses that a shrimp or other cleaner organism is eating more mucus than parasites, it violently jolts, sending a signal to both the cleaner and any other creatures around that this particular cleaner is not doing his job properly. [2]

Cost/Benefit Analysis
            This mutualistic relationship is very successful because the benefits far outweigh the costs. While an eel could typically eat, and find nutrition in shrimp, losing the nutritional value of one single shrimp in order to have all of the parasites removed from its body is a worthy price to pay. Living with fewer parasites, and therefore being healthier overall, allows the eel to hunt more productively in the long run, ensuring more food and a longer life.
            From the point of the view of the shrimp, this is an incredibly beneficial relationship because it is provided with an exceptionally easy method of finding food, while also ensuring that it does not become food for the eel. This relationship is extremely common due to its positive impact on both individuals involved.

Works Cited
[1] "California Moray." PBS. PBS. Web. 25 Mar. 2012. <>.
[2] "Diving with Moray Eels." Moray Eel Creature Feature -. Dive the World. Web. 25 Mar. 2012. <>.
[3] Hartnett, David C. "Biology Reference." Symbiosis. Web. 25 Mar. 2012. <>.
[4] "Interactions in the Reef Community." Interacions in the Reef Community. Miami University. Web. 25 Mar. 2012. <>.
[5] "Pacific Cleaner Shrimp." World Association of Zoos and Aquariums. WAZA. Web. 25 Mar. 2012. <>.

Friday, March 23, 2012

Relationship Advice: Acacia Trees and Ants

Acacia and Ants, Santa Rosa, Costa Rica 


If one is to seek relationship advice from nature, the acacia tree and acacia ants are the ones to consult! Not only do they live in very close proximity – one literally lives within the other – but both partners also depend heavily on each other for fitness. Many species of acacia tress that are deficient in chemical defenses have developed a mutualistic relationship with stinging ants in which protection is exchanged for nutrients and a home [1]. Acacia trees and their symbiotic partner can be found all over the world in temperate, desert, and tropical regions, especially since some species of acacia trees are highly invasive [2]. They reach sexual maturity typically three years after germination, and the adult trees can be used for industrial or decorative purposes [3]. During development, the acacia trees form symbiotic relationships with ants to promote healthy growth for both the ant and the tree. Not only are the trees vigorously protected, but they also provide ants and their larvae a ready home and available nutrients.     

Description of the Relationship:

Some species of acacia trees, like the Acacia macrantha of Central American, produce bitter alkaloids to ward off predators [1]. However, for those acacia species that are deficient in chemical defenses, acacia ants act as aggressive protectors. For example, Acacia cornigera (commonly known as the bullhorn acacia) found in Mexico and Central America house Pseudomyrmex ferruginea in swollen, hollow thorns [1]. The ants, with their powerful stingers, protect the trees against destructive insects, feeding herbivores, and competing vines and vegetation that pose a threat to overcrowding and sunlight availability. In return, the tree provides shelter and nutrition [4]. Ants live within the swollen, hollow thorns of the tree, and the tree produces nutrients: protein-lipid Beltian bodies from its leaflet tips and carbohydrate-rich nectar from glands on its leaf stalk [1].
A hollow, swollen thorn: home for the ant larvae.!i=575648985&k=FG4cj
A Beltian Body. 
The acacia trees that produce alkaloids grow slower than the ant-protected acacia trees because of the allocation of resources and energy. Additionally, they must grow in drier habitats where the competing vegetation grows slower since they do not have the ant gardeners [1]. Therefore, evolutionarily, this mutualistic association developed as a means to increase the fitness of both partners. Ant-plant mutualism is not rare with at least 100 other species of plants and ants exhibiting this relationship [5]. Not only can the acacia trees grow faster without any threat from insects, herbivores, and other plants, but the ants can also develop with a plentiful source of nutrition and shelter.

The mutualistic relationship is established when a newly mated queen is attracted to a tree by its odor and starts nesting inside the large, hollow acacia thorns. She lays 15-20 eggs to produce the first generation of workers. As the colony grows, more thorns become inhabited, and when the colony reaches around 400 individuals, the ants start to protect the plant [5]. The mutualistic relationship develops at this time, when both the tree and the ants benefit from the other. The association between these two partners perfectly describes mutualism because, as Claude Combes describes in our text, this bond develops “with reciprocal benefits” (11) [6].

Cost/Benefit Analysis:

In this mutualistic association, the benefits obviously outweigh the costs. The benefits to the trees include protection from feeding insects and herbivores and from competing vegetation. Costs include energy and resources used to make the nutritious Beltian bodies for the ants. They have no known function other than to provide food for the ants [1]. Acacia drepanolobium (commonly known as the whistling thorn acacia) in South Africa is called home by Crematogaster mimosa, but the tree does not provide Beltian bodies, so the ants have to forage for food elsewhere. Therefore, the ants allow insects to feed on the tree and do not provide aggression protection [1]. However, because the benefits of mutualism provide an increase to fitness, some acacia trees have developed a means to maintain the mutualistic relationship. Most plant species contain sucrose in their nectar and sap, but acacia trees provide their ants with nectar containing digested sucrose (glucose and fructose). Therefore, through evolution, some acacia ants have lost the gene encoding for the enzyme required to digest sucrose, invertase [4]. This means that these ants are bound to the tree since the only food source they can utilize is the acacia tree nectar.

Similar to the costs for the tree, the cost for the ant includes energy usage in providing protection and defense for the tree. The benefits, however, include shelter and a readily available source of nutrition. The ants require less energy in finding a suitable home for their larvae to develop, and they are not required to forage extensively for food. Therefore, the energy used in protecting the tree is compensated for by the energy saved in other tasks, so the benefits outweigh the costs. The same logic applies for the acacia tree. Less energy is devoted to producing chemical defenses, so more energy can be applied to producing food for the ants. Therefore, this mutualistic relationship works amazingly well!


[1] Wolffia. "Central American Swollen-Thorn Acacias."Wayne's Word. Web. 22 Mar 2012. <>.

[2] Brennan, John. "Relationship Between Acacia and Ants." eHow. eHow, Web. 22 Mar 2012. <>.

[3] Richards, Bailey. "Acacia Development." eHow. eHow, 11 Apr 2011. Web. 22 Mar 2012. <>.

[4] Cheshire. "Cheshire: Insects, Evolution, and Random Splatters from the Windshield of the Blogosphere." 26 Feb. 2009. Web. 22 Mar. 2012. <>.

[5] Piper, Ross. Extraordinary Animals: An Encyclopedia of Curious and Unusual Animals. Westport, CT: Greenwood Press, 2007. 1-3. Print.

[6] Combes, Claude. Parasitism: The Ecology and Evolution of Intimate Interactions; Translated by Isaure De Buron and Vincent A. Connors; with a New Foreword by Daniel Simberloff. Chicago: University of Chicago, 2001. Print. 

Thursday, March 22, 2012

A Free Ride Under the Sea: Barnacles and Baleen Whales

The barnacles and whales share a commensal relationship. Charles Darwin. Ring a bell? He was known to be a major contributor to the research of the lives of these barnacles (Cirripedia). In the earlier years, the Cirripedia was classified in the same category as crustaceans because of their outer shell. However, a major difference that was found that put the Cirripedia in a different category was its hermaphroditism characteristic (1). They are known to be invertebrates, meaning a host is essential to travel. The barnacles attach themselves to the whales as the whales make their way across the sea for nutrients and new habitats. These hermaphrodites consist of six free-swimming plankton naupliar stages (4). Even though the barnacle eggs can self fertilize, it is more likely for another barnacle to fertilize it.  However, it is as adults when they are able to attach to the hosts for an adventure around the sea (2).

In the life cycle of the barnacle, the last larval stage is known as the cyprid stage. This is the stage before it goes into its adult stage. As adults, the barnacles have “six pairs of feathery thoracic limbs” (4), which helps them grab their food and nutrients while being attached to the whales and traveling under the sea. They produce a "sticky cement" which helps the barnacle stay on the whale without falling off, under the ocean. At first, they attach anywhere on the whale, but then they find their way around particularly near the nostrils or fin, where water is easily accessible (3).

The barnacles (Cirripedia) and the baleen whales (Mysticeti) share a commensal relationship. This relationship is not particularly unique to only barnacles and whales. The barnacles can have many other hosts such as sea turtles and other marine animals.  However, there are two main important reasons why the barnacles and whales share this commensal relationship. Their main motive is to be able to find nutrients as they travel across the sea with their host, particularly, the whale. These barnacles are known to be suspension feeders. The outer shell of the barnacle consists of certain "plates" that helps them draw water into their shell (2). Another reason barnacles attach themselves to the host is to migrate to different locations. Once they attach to a host in their adult stage, they remain there for three to five years (2).  Even though the barnacles are attached to the host throughout their life span, they are being migrated to different habitats without the use of their own energy.This is an example of phoersy that Claudes mentions in his text (5).

In this commensal relationship, the whale is not highly affected. According to the whale, the barnacles are simply unnoticed. However, a slight noticeable cost for the host is the annoyance and itchiness that is caused by the barnacles (4). A major benefit for both these creatures is that they both are filter feeders. While the tooth-less baleen whales feed mostly on plankton, the barnacles pretty much eat whatever comes their way, also consuming plankton (2). The benefits outweigh the costs for the barnacles. A benefit for the barnacle is that it gets its food as it travels on the host. It does not have to go looking for its nutrients, as many others do. It pretty much grabs what it can as it rides on its' host.  The barnacle does not have to expend its own energy to get its nutrients. Another advantage for the barnacle is its ability to find different habitats under the ocean.  According to Claudes, "two clear advantages to having a living habitat is having a stability of the enviornment and protection aganist predators" (5).  Even though, attachment is crucial for the life of the barnacle, energy is preserved as it relaxes and travels along with the host. It's like a free ride across the sea!


[1] Richmond, M.. The complete work of charles darwin online. N.p., 2007. Web. 22 Mar 2012. <>. 

[2] . "Barnacle." a-z-animals. OpenCrypt Membership Software, 2008. Web. 22 Mar 2012. <>. 

[3] Grunbaum, M.. How do barnacles attach to whales?. N.p., 2010. Web. 22 Mar 2012. <>. 

[4] Kraft, Carolyn. "Barnacles: Living on a Whale." Wild Things. N.p., 22 01 2010. Web. 22 Mar 2012. <>. 

[5] Combes, Claude. Parasitism: The Ecology and Evolution of Intimate Interactions; Translated by Isaure De Buron and Vincent A. Connors; with a New Foreward by Daniel Simberloff.
            Chicago: University of Chicago, 2001. Print.

[6] DEseagrant. Barnacle Seatalk. N.d. Video. Youtube

[7] Carlos Minguell. The Barnacle: A different way of life. N.d. Photograph. Oceana

Tuesday, March 20, 2012

Helogale parvula and Bucerotidae: Friends ‘til the End!


The dwarf mongoose and hornbill bird share an interesting mutualistic relationship for several reasons. Their spectra of prey and predators are nearly identical (4), making this relationship even more important for both parties involved. In this partnership the hornbill bird eats the leftover insects during the foraging process of the dwarf mongoose (3). In exchange for food, the hornbill warns the dwarf mongoose if a predator is approaching. Both dwarf mongooses and hornbill birds are distributed in much of southeast Africa (2). In regard to their lifecycles, dwarf mongooses reach sexual maturity at one year of age and usually produce an average of five pups per litter (2). Hornbill birds usually form monogamous relationships and usually lay six eggs per birthing cycle (5). Additionally, dwarf mongooses generally sleep in old termite mounds, and hornbill birds can usually be found in the trees above these termite mounds awaiting for the dwarf mongooses to wake up and start foraging for food (4)

Description of the Relationship:

Helogale parvula (dwarf mongoose) and Bucerotidae (hornbill bird) have such a close relationship that they almost seem to seek each other out in their daily lives (4). In the morning, hornbills wait for the mongooses to awaken and when the mongooses start foraging for food the hornbills happily eat the leftover insects (3). Since the mongooses are foraging for food it is up to the hornbills to warn the mongooses of approaching predators like a black eagle. Anne E. Rasa states in her paper that, “This is the closest known mutualistic relationship known between social vertebrates normally living independently (4).” Therefore, in regard to the evolutionary history of the relationship, it can be assumed that this partnership has increased the evolutionary fitness of both parties involved. The relationship is established by the mongoose providing food for the hornbill and the hornbill providing protection for the mongoose (5). Our text explains mutualism as “opposed to parasitic systems, in a mutualistic system each partner takes advantage of the association between the two protagonists (1) (Claude Combes, 553).” It is clear that the mongoose and hornbill fully exemplify this definition of mutualism.

Cost/Benefit Analysis:

When conducting a cost/benefit analysis in mutualism it is important to bear in mind that, in most cases, the benefits outweigh the cost. The cost for the dwarf mongoose in this relationship is decreasing the total amount of food it is able to intake because the hornbill birds are eating from their same food supply (2). The benefit for the mongoose is protection from predators when the hornbills willingly signal a warning call. The cost for the hornbills is using valuable energy to signal a warning call for the mongooses to be warned of approaching predators (3). However, the benefit for the hornbills is the ease of finding excess food, in the form of easily accessible leftovers, when the mongooses are out foraging. The benefit of the hornbills outweighs the cost in that simply finding food is more valuable than the lost energy in providing the mongooses with a warning call. The benefit of the mongoose outweighs the cost in that it is better to have a slightly decreased food supply compared to being killed by a predator. Moreover, a specific strategy employed by the hornbills to ensure participation of the mongooses is living in trees close to termite mounds and waiting for the mongooses to wake up to begin foraging for food (4). Overall, the mutualistic relationship between the dwarf mongoose and the hornbill bird is one that contains a relatively low cost and reaps a relatively high reward. 


(1) Combes, Claude. Parasitism: The Ecology and Evolution of Intimate Interactions; Translated by Isaure De Buron and Vincent A. Connors ; with a New Foreword by Daniel Simberloff. Chicago: University of Chicago, 2001. Print.
(2) "Dwarf Mongoose." African Wildlife Foundation. Web. 17 Mar. 2012. <>.
(3) "Hornbill Family Bucerotidae." Don Roberson Creagrus. Web. 17 Mar. 2012. <>.
(4) Rasa, Anne E. "Dwarf Mongoose and Hornbill Mutualism in the Taru Desert, Kenya." Behavioral Ecology and Sociobiology 12.3 (1983): 181-90. Print.
(5) "Red-billed Hornbill." World Association of Zoos and Aquariums (WAZA). Web. 17 Mar. 2012. <>.