jmalloldiaz's blog

We examined color preference between cyan and green backgrounds, and white or yellow backgrounds. Cyan is a combination of green and blue at their highest intensities, while green is one of the primary colors in the RGB color model. Since we used a darker morph of crab spider for the cyan versus green trials, we hypothesized that the spider would prefer the green background.

White is a combination of the three primary colors at their highest intensities, while yellow is made with red and green at their highest intensity. Since we used a white morph of crab spider for the white versus yellow trials, we hypothesized that the spider would prefer the white background.

The term crypsis englobes a multitude of strategies for avoiding detection by other animals by blending in with their environment. It plays an important role in predator-prey relationships, such as the interactions between crab spiders and bees. In this study we used a close relative of Misumena vatia, a crab spider widely studied for its color changing abilities, to investigate background color preferrence in swift crab spiders (Mecaphesa celer).

Like other crab spiders, Mecaphesa celer is an ambush hunter and it preys on pollinator insects by lurking in the flowers they visit. We hypothesized that in order to successfully capture its prey, Mecaphesa would choose to hide in flowers that more closely resemble its actual body coloration. In order to test our hypothesis, we designed an arena split into two different colors based in the RGB color model, and recorded to which side the spider moved after being placed in the center.

The goal of this review is to focus on selected new approaches and techniques for understanding how fish move through the water and to put these recent results into the context of classical studies of fish swimming. In particular, the review focuses on the analysis of the motion of the center of mass (COM), new approaches to imaging water flows in three dimensions (3D), and fish robotics as a means to understand the physical principles underlaying aquatic propulsion.

Changes in fin and body shape occur during fish locomotion, and can be used for studying patterns of fluid flow and developing computational fluid dynamic models of swimming fish. Undulatory swimming results in increased water velocity in the caudal region of the fish. The general form of the body wave that is produced during such movement is very similar among a diversity of fishes, such as the clown knifefish, eels, and bluegill sunfish.

The researchers did not provide a definite sample size for the number of sharks used in the experiment, which could be useful for supporting that the data is reliable. As well, the passive swimming data was collected during the surgery recovery period, which could influence the shark’s performance during the trial. Instead, the researchers could have ran the trials after giving a period of rest to the sharks. Regarding the methods employed in collecting, hook and line fishing can cause injuries in the sharks, which could cause stress and become another variable to control. Other alternative methods of fishing such as employing nets could reduce the risk of injury and no longer suppose a stress factor once the shark has been released from the net. Finally, the specimens used in the experiment were probably juveniles, since they measured between 80 and 112 cm in total body length, but adults measure around 3.2 meters. Thus, the actual kinematic data for adult mako sharks will probably vary from the results obtained in the study.

The lateral motion data suggests that mako sharks are kinematically closer to tuna than other sharks. As supported by sonomicrometry recordings, during active swimming mako sharks detach their red muscles from the neighbouring tissues and focus their motion towards the posterior region of their body. Such mechanism has been found to be reciprocal in tunas, which recruit their deep red muscles in a similar fashion to power their caudal region. Nonetheless, mako sharks rely on their hypaxial lateral tendon for producing such movement, while in tuna the tendons that perform this task are found in the horizontal septum. Thus the researchers conclude that the locomotion systems of lamnid sharks and tunas arose independently by convergent evolution.

Critique

“In the recovery period we recorded red and white muscle strain during passive, simulated swimming movements.” – data collected during surgery period

“The sharks were collected by hook and line” – sharks arrived to the experiment site with injuries…

The researchers didn’t mention the exact total number of sharks they used in the experiment, if we don’t have specific sample size information we can’t tell if the data is reliable or not.

The lateral motion data suggests that mako sharks are kinematically closer to tuna than other sharks. As supported by sonomicrometry recordings, during active swimming mako sharks detach their red muscles from the neighbouring tissues and focus their motion towards the posterior region of their body. Such mechanism has been found to be reciprocal in tunas, which recruit their deep red muscles in a similar fashion to power their caudal region. Nonetheless, mako sharks rely on their hypaxial lateral tendon for producing such movement, while in tuna the tendons that perform this task are found in the horizontal septum. Thus the researchers conclude that the locomotion systems of lamnid sharks and tunas arose independently by convergent evolution.

The data displayed a small degree of lateral motion between ~0.4L and ~0.8L in mako sharks, and a substantial gain in its amplitude after ~0.8L. Regarding the sonomicrometry results, red and white muscle have a synchronous motion during passive swimming. Meanwhile, in active swimming read and white muscle action were not synchronous.

Tunas and lamnid sharks are characterized by their morphological similarities and their ability to sustain intensive exercise over prolonged periods of time. Such feats are capable thanks to the aerobic or red musculature, which relies on oxygen and provides endurance. It is known that tuna physically uncouple their red muscle and project it towards posterior regions of the body to produce their thunniform-like swimming. Nonetheless, tunas and lamnid sharks are distantly related and acquired their thunniform body shapes and aerobic capabilities independently, making them a case of convergent evolution.

The locomotor system of tunas has been recently investigated, but prior to this study there was a gap in the knowledge regarding that of lamnid sharks. The objective of this study was to learn more about the dynamic properties of the locomotor system of lamnid sharks. Due to sharing morphological and locomotive similarities with tuna, the researchers hypothesized that the force-transmission system of tunas is also found in lamnid sharks.

Both songbirds and humans are primed towards learning their species vocalizations and filter out the rest of sounds during the learning process. They both go through a critical learning period or sensitive period, during which information is stored for use in later stages of learning. Oscines also have a subsong period which is analogous to infant babbling and connects the perceptual and sensorimotor stages of vocal learning. Finally, there is a crystallization period, during which plastic song or language is perfected into the standard vocalizations of the species.