BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: predator-prey

How are ocean conditions harming its animals?

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On January 21, 2020

In Student Post

A recent article written by Rachel Nuwer discusses the dangers of ocean acidification and how the ocean environment could compromise the fishes’ ability to swim and feed. The existence of one of the world’s most threatening predators is being threatened by ocean warming and acidification. Sharks might lose their place at the top of the marine food chain due to the changing ocean environment. As carbon dioxide levels rise in the ocean, it increases the acidity of the water. As this factor starts to rise, the teeth and scales of sharks may begin to damage, which compromises their ability to swim, hunt, and feed. According to research published in Scientific Reports, acid-base adjustments have proved to be the first piece of evidence of “dentical corrosion” caused by ocean acidification conditions. After investigating the impact of hypercapnia on a specific shark species and analyzing the acid-based regulation, the team concluded that the denticle corrosion could increase denticle turnover and compromise the skin and protection of the shark species.

A close up on the denticles and scales of a wild shark

The harsh conditions placed on the sharks could cause several consequences and ultimately could affect the whole ocean community. Biologist Lutz Auerswalk states that sharks could be displaced as apex predators, which could disrupt the whole food chain. In addition, great white sharks are already endangered, and these conditions could wipe them out completely, he states. Ocean research Sarika Singh and Auerswald, while studying over beers, stumbled upon a unique idea. After realizing that the high acidity of beet and many other carbonated beverages causes human teeth to erode, they wondered what effect more acidic ocean water might have on shark teeth.

Most studies on ocean acidification examine species that specifically build shells or other calcium-based structures, including corals and shellfish. Because sharks are large and challenging to work with, only a few studies have been conducted about how acidification might impact these animals. Only one paper has examined the effect of pH on sharks’ skin denticles or scales. The study used small-spotted catsharks and exposed them to different environments and filmed their swimming patterns. After analyzing a pectoral fin skin sample, they did not find a specific impact. However, the results were possible constrained by the low carbon dioxide concentration the researches used, compared with the high levels of acidity already present in many oceans.

To begin exploring this question for themselves, Auerswald and Singh conducted an experiment and focused on puff adder shy sharks, a small species that is easy to handle. They decided to investigate the acidification effects on the bigger scales. They divided the sharks into control and experimental groups and observed the results. After a few months, the electron-microscope analysis revealed that the concentrations of calcium and phosphate in the sharks’ denticles were significantly reduced. They noticed damaged scales on many of the sharks as well. Though the corroded scales might not impact their ability to hunt, for larger species such as the great white shark, scales play an essential role in hydrodynamics. Because denticles are responsible for an increase in swimming speed, damaged denticles could slow sharks down and make it more difficult for them to catch prey. Because many animals have been wiped out, we must strive to protect all the species that are deeply impacted by this condition.

Guppy Social Circles: The Evolutionary Benefit of Tight-Knit Groups

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On March 1, 2017

In Student Post

It is often said that humans are social creatures.  But why is this?  How do other species help substantiate the need for social interaction and friendship among humans?  What direct benefits result from strong ties between individuals?  To grapple with these questions, Rob Heathcote, an animal behavior researcher at the University of Exeter, conducted the following experiment.

Guppies swimming in a group of three by Per Harald Olsen, source

Heathcote and his team traveled to Trinidad, an island in the Caribbean that is home to the small freshwater Trinidadian guppy.  But why this place and this species you might be asking.  In response, Heathcote states that, “These guppies live in environments that have tons of predators around, so basically it really sucks to be a guppy. In some places they live, you’ll be watching these shoals of guppies and a predator is attacking them every twenty or thirty seconds or so.”  With the hypothesis that animals form social groups in order to reduce the risk of being preyed upon, the Trinidadian guppy was the perfect specimen.  However, Heathcote sought to investigate whether the benefits of communal living derived from individual relationships (as in humans) or simply safety in numbers.

The team divided 240 female Trinidadian guppies into smaller groups of fifteen, with each group having its own pool isolated from the rest.  Some fish were left alone while others were spooked with a doll version of a predator known as the pike cichlid.  It was recorded that the groups formed by the guppies exposed to the faux predator were smaller on average when compared to the groups that the unprovoked fish formed.  Therefore, one can conclude that the startled guppies fearing for their lives were more likely to establish stronger social connections between one another.  In other words “Fear of predation drives stable and differentiated social relationships in guppies” (Heathcote et al. in Scientific Reports).

So, guppies can congregate in massive groups to blend and reduce their chances of becoming dinner.  However, congregation itself attracts more and more predators.  Alternatively, as seen in the experimentation, they can hide in smaller social circles of three to four individuals, a sort of family where each guppy has each other’s best interest in mind and where the guppies can effectively communicate.  When drawing parallels between the Trinidadian guppy and humans, it is clear that both species form exclusive clans to ameliorate their lives.  In the words of Jason G. Goldman, “Spending time with a few close friends could outweigh the benefits of blending in with the crowd, particularly in dangerous situations.”

The research results in many follow up questions.  Why do some humans choose to isolate themselves from social interaction altogether?  How can this study relate to international relations?  What really makes humans different from more primitive species?

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