Effects of Antidepressants on Fish, by Tal Tomlinson

Many people throughout the United States deal with personal issues like depression on a daily basis. Awareness and the scientific study of mental illnesses has risen within the past decade. Luckily, there are doctors who can talk patients through their struggles and, if necessary, prescribe them antidepressant medication to make their lives as peaceful as possible. Prescribed medications contain different chemicals that affect the nervous system in many ways. However, medications such as antidepressants have uncertain effects in the aquatic environment. For example, the chemical ingredients released from prescribed medications can have negative effects on fish behavior and their neuro systems.

Fish as a species have been studied for hundreds of years dating back to the incorporation of fish in Aristotle’s scientific studies in 330 AD (Aristotle & Balme 1991). Their anatomy, physiology, and ecology have been consistently studied by environmentalists since the evolution of technology. However, due to the recent improvements and the introduction of substances like antidepressants, scientists have only begun studying their neurological effects on fish due to a fluctuation in observed behaviors. Fish are known to have a fairly simple brain, but they can still process semi-complex situations like interacting and avoiding predators. At this time, scientists are trying to figure out why these interactions and relations have decreased.

Fathead Minnow were prey species in study of predator avoidance by Painter et al. 2009.  Photo by Ted Fauceglia.

Antidepressants (citalopram, paroxetine, sertraline, venlafaxine, and bupropion, and their metabolites norfluoxetine and norsertraline) were detected in gonad, brain, muscle, and liver organs of Largemouth Bass and other fishes from Niagara River (Arnnok et al. 2017).   Photo by Neil DeMaster. CC BY-ND- 2.0

In one study by investigators from the Université de Montréal, it was found when bodies of water are contaminated and fish are exposed to anti-depressants, they begin to exhibit a reduction in prey avoidance behavior in Fathead Minnow Pimephales promelas. This is due to the inhibition of specific neurotransmitters, such as “…serotonin (5‐hydroxytryptamine; 5‐HT), norepinephrine (NE), and dopamine (DA)” which are blocked or altered by the contaminant (Painter et al., 2009).  All of these chemical hormones are crucial to both the central and peripheral nervous system of the fish. If there are even slight changes in the neurological concentration of the body from outside sources, it could affect many different intrinsic systems. One of which is the behavior of complacency toward predator threats. Antidepressants and prescribed medications cause a panic in the fisheries science community because many of the ingredients that make up the drugs are serotonin inhibitors. Serotonin, a neuro hormone found in both human and fish brain tissue, is used to regulate emotion, sleep cycles, and even the “fight or flight” response when posed to threats. When antidepressants are introduced into an ecosystem at a human specific concentration, between 5-40 mg depending on body size (Phelps 2015), it can completely destroy the neurotransmitters that the chemicals adhere to due to overload. This in turn causes the behavioral complacency.

Venlafaxine affected predator avoidance behaviors of Fathead Minnow (Bisesi et al. 2014).

Complacency is an issue due to the fact that fish who reside in a watershed where antidepressants have been introduced may also interact with fish from other areas who have not. Once in this environment where all other fish have normal behavior, the changes become apparent. Fish species who have not been altered by the effects of antidepressants are able to attack and prey upon the newly affected fish. Due to the destruction of the chemoreceptors in the brain, they begin to lack fear and swim towards predators. However, these affects also work in the opposite direction. Fish species who have been affected by the ingredients of antidepressants have a significantly decreased ability to catch prey and feed.  Bisesi et al. (2014) found that bass who were exposed to venlafaxine, a commonly prescribed antidepressant, showed increased prey capture time in all 6 of their studies. They were beginning to capture prey at a much slower rate than if they had not been affected. Another effect they found to be true was that with the introduction of venlafaxine, there was a statistically significant reduction in the serotonin found in brain tissues of fish (Bisesi et al. 2014). Its exposure to the watersheds has become detrimental to fish neurosystems and behavior. Despite their hypothesis being proven, they are left with mostly open-ended data. In their conclusive statement they confer, “Brain serotonin alone did not adequately explain behavioral results. Serotonin response in other tissues as well as peripheral effects may have accounted for additional behavioral responses after brain serotonin reached a depressed steady state.” (Bisesi et al. 2014), thereby explaining that more studies must be conducted in the same manner to have conclusive and evidential proof.

Understanding the behavior of the fish and how these chemicals affect them is extremely important. However, it is also very important for us to understand how these chemicals are getting into the environment. If no solution is found to address this issue, there could be serious declines in fish populations in the future due to the change in behavior observed in fish that have been exposed to antidepressants. The chemicals making up these substances are causing fish to become complacent and not willing to feed or mate. These are serious issues which need to be addressed in order for fish to live normally. Eliminating these adverse side effects are critical in order to maintain healthy ecosystems, maintain species diversity and preserve the sport of fishing. Improved processes  more effectively removing these medications and their metabolites from wastewater are needed to prevent the loss of biological diversity in our lakes and rivers (Arnnok et al. 2017).

References

Aristotle, and D. M. Balme. 1991. History of animals. Harvard University Press, Cambridge, MA.

Arnnok, P., R.R. Singh, R. Burakham, A. Pérez-Fuentetaja, and D.S. Aga.  2017. Selective uptake and bioaccumulation of antidepressants in fish from effluent-impacted Niagara River.   Environmental Science and Technology 51:10652-10662.  

Painter, M. M., M. A. Buerkley, M. L. Julius, A. M. Vajda, D. O. Norris, L. B. Barber, E. T. Furlong, M. M. Schultz, and H. L. Schoenfuss. 2009. Antidepressants at environmentally relevant concentrations affect predator avoidance behavior of larval Fathead Minnows (Pimephales promelas). Environmental Toxicology and Chemistry 28(12):2677.

Phelps, J. 2015. What Is an Adequate Dose of an Antidepressant?” Psychiatric Times, October 5.  Accessed on 30 April at www.psychiatrictimes.com/depression/what-adequate-dose-antidepressant

Bisesi, J.H., Jr., W. Bridges, and S.J. Klaine. 2014. Effects of the Antidepressant Venlafaxine on fish brain serotonin and predation behavior.  Aquatic Toxicology 151:88-96. doi: 10.1016/j.aquatox.2014.02.015.    

Carp Personality, by Hanna Moreland

In a study conducted by Klefoth et al. (2012) questioned whether boldness of specific carp increased capture rate through hook and line fishing.  They are not the only investigators studying personality in fish.  In this essay I explore three questions. What is boldness in carp?  How do we measure it? What are the implications of this research?  I will explore these questions in the context of the Klefoth et al. study in order to give a better understanding of why this research is so important.

Common Carp Cyprinus carpio.  Photo from Flickr.  CC BY-NC-ND 2.0

Science would be easier if we could just ask animals their personality traits through a short quiz or verbal interaction. How can a carp have a personality? One way to measure personality in carp is to identify if the individual is bold or not bold. In this study carp boldness was measured by tracking fish movements within a small pond with transmitters. In the pond there were shelters the researchers placed which the carp used for safety. Some carp spent their time mostly in the shelter, some spent some time right outside the shelters, and others ventured far from the shelter. Those individuals who ventured far from the shelter site were considered bold and marked as so for later testing. Do these individuals have a higher production of a hormone or a genetic sequence that makes them more likely to be bold?  Klefoth et al. (2017) indicates that there is a genetic component to being bold as boldness was a repeatable measurement in this experiment as well as in other experiments studying fish.

Next, I’m going to explore why measuring boldness matters in the context of this article as well as in relation to angling. Klefoth et al. (2012) asked whether boldness and catchability were correlated. They hypothesized that the bold individuals, those who ventured far from the shelters in the pond, would be more likely to be caught by anglers because they were in open waters. The research indicates that a correlation exists! Those individuals marked as bold in the first part of the study, were the carp more likely to be caught in the second half of the study. This has great implications for management strategies in both threatened species and species intended for harvest. If boldness is truly genetic and moderately heritable these traits can be selected and bred for. In relation to threatened species, individuals who stay in the shelters would be most useful for breeding purposes because they are more cautious and less vulnerable to predation. On the other hand, for game fish purposes the bold fish would be the focus of breeding and stocking programs. In this study bolder fish were more likely to be caught which means happier anglers if bold fish are stocked in popular carp fishing ponds!

 

Carp breaching.  Photo by Stan Lupo.  CC BY-NC-NC 2.0.  Source.

Of course, there are still a lot of questions that need to be answered before breeding programs can be initiated. Further research can delve into what makes a carp bold, whether it be genetic or hormone related. Next studies could focus on if boldness is heritable from parent to offspring and by what magnitude as traits like length and size are only moderately heritable in fish (Garcia et al. 2007). If these continued research efforts yield positive results this could mean new management techniques that improve populations of threatened and game carp species. Finally, similar research could be conducted on other species of fish to see if the same results hold true and can be applied to their own management programs. Fish may not be as different from humans with regards to personality. This new finding opens new windows of opportunity for bold students willing to explore these implications through further research and management.

References

Garcia de Leaniz, C., and fourteen coauthors. (2007). A critical review of adaptive genetic variation in Atlantic salmon: Implications for conservation. Biological Reviews, 82, 173– 211.

Klefoth, T., Skov, C., Kuparinen, A., & Arlinghaus, R. (2017). Toward a mechanistic understanding of vulnerability to line fishing: Boldness as the basic target of angling‐induced selection. Evolutionary Applications, 10, 994– 1006.

Klefoth, T., Skov, C., Krause, J., & Arlinghaus, R. (2012). The role of ecological context and predation risk‐stimuli in revealing the true picture about the genetic basis of boldness evolution in fish. Behavioral Ecology and Sociobiology, 66, 547– 559. 

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Exploring Pearlfishes (Carapidae) and the Pinhead Pearlfish Encheliophis boraborensis, by Jireh Clarington

 Considering the vast diversity of chordates, it may seem odd that few of them are parasitic. Particularly among fishes there are some parasitic groups, cookie cutter sharks and lampreys being the most common, but there is another group of fishes that is not as well understood: the pearlfishes. Although not all members of this family are parasitic. Commensalism is represented in this family as well.  Commensalism refers to a type of symbiotic relationships in which the individual interacts with and relies on its host for survival while the host is negligibly affected by said interaction. Pearlfish are a group of ophidiiforms in the family Carapidae with eight currently recognized genera and thirty-six species who represent each of these strategies. A pearlfish’s host often depends on the species of the fish. Some can be found parasitizing bivalves or living commensally inside tunicates others live in echinoderms like sea stars and sea cucumbers. The phylogeny of the Carapidae is still under debate as its genetic relatedness with other members of ifs genus and family are still being contested. We will be exploring the Carapidae family through the lens of one particular species: Encheliophis boraborensis formerly called Carapus boraborensis whose adult form is spent commensally inside sea cucumbers.

 

Illustration of the Pinhead Pearlfish Encheliophis boraborensis.   Source.

It may be necessary to provide a brief note on sea cucumber anatomy: sea cucumbers have a mouth on the anterior end and an anus on the posterior near the posterior is a pair of organs called a respiratory tree, these sticky organs are ejected by the cucumber when threatened and are able to produce toxins, however many pearlfish show increased resistance to these toxins compared to other reef dwelling fish. This allows the pearlfish to be protected by the cucumber without being poisoned by it. Additionally, the anal cavity is near the gonads, in the case of parasitic pearlfish these are the tissues most commonly found in pearlfish’s stomachs suggesting that parasitic pearlfish tend to eat the gonads of their host while still being able to exploit the cucumber for protection as its respiratory tree is left intact as the cucumber is able to remain healthy but the individuals fecundity could be severely reduced depending on the time needed until the gonads regrow (Parmentier and Vandewalle 2004).

Pearlfish are mainly found in the Pacific Ocean, specifically the tropics on reef habitats where their hosts can be most commonly found. The pinhead pearlfish, Encheliophis boraborensis, can be found near French Polynesia living in the cloacal vent of any number of local sea cucumber species and in some cases many pearlfish can be found in a single host (Parmentier and Vanderwalle 2004). Pearlfish such as the pinhead pearlfish rely on their sleek elongated body shapes to enter their hosts tail first to enter their host cucumbers. However, with species who inhabit hosts, such as tunicates or oysters, the orientation is less significant.

Click here to watch video of a pearlfish.  

Pinhead Pearlfish with leopard sea cucumber Bohadschia argus.  Source:  Project Noah.

When building a phylogeny, it is useful to use morphological traits as well as molecular analysis to form plausible hypotheses. Much can be said about a pearlfish’s life history based on morphology alone as, upon analysis, certain patterns arise that help distinguish the separate life strategies the fish employs. For example, jaw structure and size in the parasitic fishes tends to be weaker in comparison with commensal species. This weakening of their feeding apparatus can be attributed to the commensal species need to leave its host in order to hunt the small crustaceans on which it feeds as opposed to the pearlfish species who do not need to leave their host and are able to feed exclusively on their hosts soft tissues. Another useful morphological trait is the presence of sound generating structures connected to the pearlfish’s swim bladder (mainly used for communication with conspecifics) vary greatly (Lagardère et. al. 2005). The diversity of these mechanisms is emblematic of the speciation within the Carapidae family but offered very little in the way of clues to establish any evolutionary relationships within the taxa (Parmentier et.al. 2016). However, as previously mentioned a host may be inhabited by multiple individuals, but these may not necessarily all be members of the same species in a laboratory study by Garilao, interspecies competition was observed. Thus, it can be extrapolated that the variation in calls and sound generating structures unique to each species help distinguish one species from another and play a role in competition for a host.

To explain the relationship between parasitic and commensal pearlfish one must also consider their life history. Pearlfish larvae have two stages before reaching their final adult forms, these stages are the vexilifer larvae which are free swimming meroplankton until they reach the tenuis stage in which their bodies shorten in length and they begin to search for a host. It is believed that the parasitic species are derived from the commensal pearlfish as the result of pedomorphosis within the parasites. Pedomorphosis occurs when the adult form of a species retains traits from its juvenile forms in the case of the pearlfish this is reminiscent of the relationship between free living and parasitic lampreys where, once again, only the adult form becomes parasitic.

In conclusion, members of the family Carapidae are a diverse group of animals whose evolutionary strategy have led them to employ a fascinating range of survival tactics to live on tropical reefs. Some like Encheliophis boraborensis exhibit morphological and developmental differences that make it better suited for a commensal life with its host. While other members in different genera of the family are may have started commensal but have evolved to become parasitic rarely needing to leave their hosts body cavity. There is still more to be learned about the ecology of these fishes as little is known about their mating habits and the extent of damage their parasitism has on their hosts.
 

References

Froese, R. and D. Pauly. Editors. 2019. FishBase. Encheliophis boraborensis summary page.  World Wide Web electronic publication.   [accessed 2019 May 1]. http://www.fishbase.org/summary/Encheliophis-boraborensis.html.

Lagardère JP, Millot S, Parmentier E. 2005. Aspects of sound communication in the pearlfish Carapus boraborensis and Carapus homei (Carapidae). Journal of Experimental Zoology Part A: Comparative Experimental Biology. 303A(12):1066–1074.

Parmentier E, Castillo G, Chardon M, Vandewalle P. 2001. Phylogenetic analysis of the pearlfish tribe Carapini (Pisces: Carapidae). Acta Zoologica 81(4):293–306.  doi:10.1046/j.1463-6395.2000.00059.x

Parmentier E, Vandewalle P.  2004. Further insight on carapid —holothuroid relationships. Marine Biology 146(3):455–465.   doi:10.1007/s00227-004-1467-7

Parmentier E, Das K. 2004.  Commensal vs. parasitic relationship between Carapini fish and their hosts: some further insight through δ13C and δ15N measurements. Journal of Experimental Marine Biology and Ecology. 310(1):47–58. doi:10.1016/j.jembe.2004.03.019

A Fish With Eyes Inside Its Head, by Aaron Betancourt

The Pacific Barreleye Macropinna microstoma is a truly extraordinary fish first discovered in 1939 with an incredibly bizarre morphology unlike any other fish in the world (Robison and Reisenbichler 2008).  The Barreleye has a relatively narrow distribution for a marine fish species ranging from Western North America, to Eastern Asia (Eschmeyer et al. 1983).  This species of fish is relatively small, as most individuals are only half an inch long while larger specimens may grow to a foot and a half (Baidya 2017).  The Pacific Barreleye is an incredibly unique fish species that is best defined by its large telescopic eyes located inside its head, its bioluminescent organs, and its feeding and behavioral patterns.

The Barreleye’s claim to fame are its eyes which are located inside its head underneath a transparent dome-like hood.  These eyes resemble barrels in shape thus how the Barreleye got its name (Poulsen et al. 2016).   For quite a while after discovery, the Barreleye’s eyes were thought to be fixed in place thus leaving the fish only able to look in an upwards direction without moving its head or body; however, it has been recently discovered that these eyes are able to rotate in place allowing the Barreleye to either look up to view its surroundings, or look forwards to see where it is swimming or look at the food it is about to consume (Robison and Reisenbichler 2008).  The Barreleye lives in the deep sea and so advanced sight is a tremendous advantage that few marine fish at that depth have.  The tubular eyes of the Barreleye are filled with a fluid that makes the eyes more sensitive to light than other fish.  They can detect even the smallest bits of light enabling it to see prey in its near pitch black environment (Baidya 2017).   

 One major question about the Barreleye was why its eyes where located inside its head and not outside like most other fish.  It is now believed that the translucent covering’s purpose is to protect the eyes of the Barreleye from damage, especially from the stingers of jellyfish (Eschmeyer et al. 1983).  At first glance it may seem like the Pacific Barreleye actually has eyes on the outside of its head, but that would be incorrect to think that.  Those eyelike spots on the outside of the head are actually olfactory sacs used for smell (Baidya 2017).  Along with its sight the Barreleye uses these tools to hunt prey.  Click here to watch video of the Pacific Barreleye.

Barreleye hunting technique.    Illustration by Ocean Syrup.    CC by 2.0

Another unique feature the Pacific Barreleye possesses is bioluminescence as is common for deep sea creatures.  They have soles on their undersides which are bioluminescent organs that the Barreleye can change the amount of light emitted from (Poulsen et al. 2016).  Because there is some form of light present where the Pacific Barreleye lives—although very minimal—it has been hypothesized that due to the location of the bioluminescent organ on the underside of the fish, the soles primary purpose is to provide counter shading to the Pacific Barreleye (Poulsen et al. 2016).  This counter shading is used by the Barreleye to help hide itself from predators by making its underside match as closely in color to what little light is making it down from above so that it blends in and predators below struggle to see it (Kelley et al. 2017).  One other potential use of this bioluminescent organ is communication between individual Pacific Barreleyes, but this is much less studied due largely to the fact that the Barreleye lives in such deep water where species are much harder to study (Poulsen et al. 2016).

The morphological adaptations the Barreleye possess are key in understanding the behavior of the fish and how that behavior aids it in everyday survival.  The largest adaption the Pacific Barreleye has other than its name giving eyes, are its incredibly large pectoral fins.  The fins are shaped in a way that the Pacific Barreleye can extend them in such a way that they hit a full stop in the water and remain motionless (Robison and Reisenbichler 2008).  It is hypothesized that the Pacific Barreleye sits completely still in the water column using its incredible vision to detect the faintest bioluminescent glow of prey while using its own bioluminescence to remain undetected (Robison and Reisenbichler 2008).  Upon finding prey it then sneaks up on it and ambushes it catching the prey in its small mouth.  Prey for the Pacific Barreleye ranges from small planktonic organisms to crustaceans and even some jellyfish (Baidya 2017).  The Barreleye’s inclusion of jellyfish in its diet explain the presence of the shield over its eyes as getting up close and personal with a jellyfish could leave the Barreleye stung and its eyes damaged if not for the shield.  It is also believed that the Pacific Barreleye interacts with jellyfish in another unique way.  Robison and Reisenbichler (2008) believe that the Pacific Barreleye uses its large fins to maneuver around the stingers of jellyfish and steal prey from them by quickly plucking them away from the stingers. 

The Pacific Barreleye is an incredibly strange creature due in large part to its remarkably sensitive eyes located inside of its own head, its bioluminescent soles which hide it from predators, as well as its feeding habits of motionless hunting and stealing food from jellyfish.  Little research has been done on these remarkable creatures because of their location in the deepest waters of the ocean.  What work that has been done has been to characterize its most striking features as well as determine the true number of species of Barreleye present.  More research on these fish is needed to understand in what ways the Barreleye uses its bioluminescence to communicate, as well as to understand if there are more reasons why it has evolved its eyes inside of its own head.

References

Baidya, S. 2017, October 17. Barreleye Fish Facts: 30 Facts You Will Need For Your Homework. https://factslegend.org/30-barreleye-fish-facts-truly-bizarre/.

Eschmeyer, W. N., E. S. Herald, and H. Hammann. 1983. A Field Guide to Pacific Coast Fishes of North America. Houghton Mifflin Company.

Kelley, J. L., I. Taylor, N. S. Hart, and J. C. Partridge. 2017. Aquatic prey use countershading camouflage to match the visual background. Behavioral Ecology 28(5).

Poulsen, J. Y., T. Sado, C. Hahn, I. Byrkjedal, M. Moku, and M. Miya. 2016. Preservation Obscures Pelagic Deep-Sea Fish Diversity: Doubling the Number of Sole-Bearing Opisthoproctids and Resurrection of the Genus Monacoa (Opisthoproctidae, Argentiniformes). Plos One 11(8).

Robison, B. H., and K. R. Reisenbichler. 2008. Macropinna microstoma and the Paradox of Its Tubular Eyes. Copeia 2008(4):780–784.

Aggressive Behavior of the Sarcastic Fringehead, by Brittany Bailey

The Sarcastic Fringehead is a tube blenny (Chaenopsidae) that lives along the Pacific Coast, ranging in area from San Francisco to Baja California (Aquarium of the Pacific N.D.) They live in rocky crevices and shells leaving only their head exposed. In addition, they often find homes in abandoned holes or burrows, empty clam or snail shells, and old cans and bottles (Aquarium of the Pacific N.D.) One resides in almost every bottle in the “beer bottle field” in Santa Monica Bay, California (Aquarium of the Pacific N.D.) Despite the name, this bizarre fish is anything but sarcastic or comical. Neoclinus blanchardi, the Sarcastic Fringehead, is one of the most fascinating fish in the world because of its body shape and size, unique mouth, and aggressive behavior.

Sarcastic Fringehead Photo by Ken Bondy  CC BY-NC-SA 2.0 Source

Neoclinus blanchardi have very unique body characteristics. Their body is slender, elongate, and moderately compressed (Aquarium of the Pacific N.D.) They live to be about 6 years old and grow to be around one foot in length, but typically stay around 3 to 9 inches (Aquarium of the Pacific N.D.)  Sarcastic fringeheads are the largest of the thirteen fringeheads Neoclinus spp. They possess characteristics of a long dorsal fin, wavy, fringe-like cirri, or appendages, on their heads, and prominent lips (Aquarium of the Pacific N.D.) These fish have unbranched pectoral fin rays, an extended dorsal fin continuously from the head to the base of the caudal fin, and an anal fin extended from the vent to the base of the caudal fin (Aquarium of the Pacific N.D.). Their dorsal fins have spines that have two ocelli, one between the first and second spines, and the other between the fifth and ninth spines (Aquarium of the Pacific N.D.) Ocelli are eye-like spots and are generally blue and outlined by a yellow ring on the sarcastic fringehead (Aquarium of the Pacific N.D.). Fringeheads are generally brownish-gray and typically mottled and blotchy with black, brown, gray, purple, red, or green patches (Aquarium of the Pacific N.D.). Even with all of these features, they are specifically known for their extremely large mouths and temperment.

The mouth of the sarcastic fringehead is one like no other. They characteristically have a long maxillary that extends to the back edge of the gill cover (Hongjamrassilp et al. 2016). The jaw extends past the eye and is smaller in females than in males, which makes a lot of sense because the males do most of the fighting (Aquarium of the Pacific N.D.). Because they do not have good eyesight, they will send a warning with their mouth to practically anything they feel threatened by. This includes animals that are much bigger than them, including humans (Aquarium of the Pacific N.D.). Neoclinus blanchardi has a large colorful mouth and terrifying territorial tendencies. Even those these fish are smaller, they have terrifying defensive mechanisms all stirring from this extraordinary mouth.    

Sarcastic Fringhead displaying its large mouth.  CC BY-SA 4.

While the fringehead’s jaws might look excessive and unproperly sized for their body, they are quite useful when fighting over territory. Overall, blennies, like the sarcastic fringehead, are mostly sedentary and stay inside of their shelter with little movement, but they have no problem jumping into action when necessary (Hongjamrassilp et al. 2016). They are so aggressive because they want to defend their home territory from intruders. In addition, females lay eggs inside of the male’s burrows, which the male will aggressively guard and protect (Hongjamrassilp et al. 2016). When two fringeheads meet, they lunge at each other, with their mouths open, almost like a “kiss”. This peculiar behavior helps the fringeheads size each other up; the bigger fringehead is always the dominant one because of their larger mouth and jaws (Hongjamrassilp et al. 2016). 

Sarcastic Fringeheads are tempermental fish, but their rivals face something very unique, a gaping, fluorescent mouth (Hongjamrassilp et al. 2016). When threatened by another male, the fish opens its mouth about as wide as its head, displaying multiple rows of needle-like teeth (Aquarium of the Pacific N.D.) In addition, they will also aggressively attack anything that comes near their nook. The fringehead also has one of the most unusual ways out of all the animals in the ocean to settle territorial disputes. If a fringehead moves into an area where another fringehead is living, they “mouth wrestle” for the area. Click here for video.  This involves them pressing their open mouths against one another to fight, and the fish with the bigger mouth wins the territory (Hongjamrassilp 2016). To start the fight, the fish sends a series of warning signals by adopting a threatening and hostile look. First it flexes its body, extends its gill covers until they pop up like an umbrella, and then snaps its jaws (Hongjamrassilp 2016). It is a continuous process until one of the fish wins. They are extremely brave, territorial, and defensive, and use this mechanism to show it.

 

Lateral view of the Sarcastic Fringehead.  Photo by Ben Cantrell.  Source.

Neoclinus blanchardi are extremely different fish. They enjoy burrowing in discarded cans and other trash. Their mouths are incredibly large for their size, and they have the strangest mechanism for attacking other fish and predators that they feel intimidated by. They live their life in a hole, causing a lot of problems simply because something gets too close to their home territory, and the males go out of their way to protect the eggs in their shelter. However, they are still very fascinating, and more research should be collected to find out more about the Sarcastic Fringehead because there is very minimal research conducted and published now.

References

Aquarium of the Pacific. N.D. Online Learning Center. Website.  April 28, 2019. https://www.aquariumofpacific.org/onlinelearningcenter/species/sarcastic_fringehead.

Hongjamrassilp, W., A.P. Summers, and P.A. Hastings. 2016. Heterochrony in fringeheads (Neoclinus) and amplification of an extraordinary aggressive display in the Sarcastic Fringehead (Teleostei: Blenniiformes).  Journal of Morphology 79(5):626-635. doi: 10.1002/jmor.20798