Erin Snyder
November 23, 2015
BIOL 112
Dr. Irish
How does the Blue-ringed Octopus (Hapalochlaena Lunulata) Flash its Blue Rings? Journal Article Summary
Introduction
The blue-ringed octopus uses an interesting technique to ward off its predators. Utilizing aposematic coloring (a warning mechanism), this creature can let other animals know to stay away. The tiny cephalopod bears about sixty bright blue rings, appearing as a pattern on its dermal covering. When these rings flash, one can tell that the octopus has been threatened. Although this tropical marine creature may generally be calm, when it is agitated, it can bite with its beak and inject tetrodotoxin into the blood stream. This venom can quickly kill an adult human. Typically, the blue-ringed octopus, or Hapalochlaena Lunulata, resides among rocks and shells on the ocean floor and exhibits a camouflaged appearance (Mathger et al., 2012). However, its skin contains many more interesting structures that allow it to have such a distinct presentation.
Many cephalopods have camouflage techniques and use aposematic coloring as well. The two methods they can use to accomplish this kind of coloring are either through chromatophores and pigments or structural reflectors (Mathger et al., 2012). Chromatophores are organs that have pigment sacs.
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Pigment sacs contain different colored pigments and can be controlled neurally. Radial muscle fibers attach to the pigment sacs. When the octopus feels threatened, neural impulses will be sent to contract the muscles, causes the pigment sacs to enlarge and release the color. Likewise, when the muscles relax, the pigment sac will pull back and return to its camouflaged state. In cephalopods, the main structural reflectors are leucophores and iridophores. Leucophores are responsible for the pale coloring in cephalopods by refracting light. Iridophores have plates that reflect colors and contain proteins scattered throughout the cytoplasm, allowing them to hold a large array of reflective properties. Through this mechanism, iridophores are able to display colors throughout the entire visible light spectrum (Mathger et al., 2012). Methods Mathger and colleagues investigated the method through which the blue-ringed octopus displays its iridescent rings, and how they work (2012). This question is interesting to be asked since the method by which the octopus actually is able to flash its rings has never been investigated in prior scientific experiments. To conduct their research, blue-ring octopus specimens were anesthetized. The reflectance of the samples was measured by a fiber optic spectrometer, and recorded against whiteness on a spectrum. Next, the scientists measured how the flashing blue rings were activated from a physiological standpoint. Samples of to octopus tissue were carefully fixed into cross sections using scientific procedures. To view them, they used electron, brightfield, and confocal microscopy. In addition to the microscope slides created, the authors also filmed six adult blue-ringed octopuses (Mathger et al., 2012). Results The scientists discovered that the blue-ringed octopus has a very unique foreboding display.
Suggested by its name, the octopus’ sixty or so blue rings light up in an iridescent fashion. The colorful rings extend from the head down to the body and arms of the creature on an otherwise dull body. As observed by the recorded video of the octopuses being disturbed, the rings were quick to light up with a dark brown colored outer circle, and a blue-green center. This display could be accomplished in as fast as 0.3 seconds, up to a little over 0.5 seconds. They noted that this brown ring of chromatophores along the edge increases the distinction between the rings and the pale
skin. From the cross sections of the dermal covering, Mathger and colleagues explained that iridophores are responsible for the bright colors inside of the rings (2012). Chromatophores compose the dark rim of the rings, as well as the main area of the body. Iridophores are found in folds in the skin, or pockets in the skin. These areas are typically covered, but during rapid body responses and neural stimulation, these pockets can open up to be discovered. There was interest in the parts that composed to blue rings. Muscle fibers, including transverse muscles and perimeter muscles are responsible for the viewing of iridescence. Muscle fibers typically contract to close this pocket, but when agitated, the transverse muscles will relax and these perimeter muscles will contract so the bright blue color is visible to the octopus’ predators. The scientists also measured different angles of reflection in the iridophores. Iridophores that compose the blue rings contain many reflective plates on many layers of the cell. Normally, the rings reflect at 500 nanometers. Finally, neurotransmitters that stimulate other cephalopod’s body patterns were added to the skin samples. They found that there were no changes in the iridescence with any of these neurotransmitters. Discussion From the results of the experiment performed by Mathger and colleagues, they determined that the blue-ringed octopus’s rings main components that allow color change to be possible are pigmented chromatophores and structural reflectors. Chromatophores react almost spontaneously because they are under neural control. Leucophores remain inert, however iridophores can be modified in color and intensity of that color. The colors and iridescence can be adjusted by chromatophores that prohibit the warning colors to be shown indirectly, as well as receptors that modify the intensity of the color displayed. The aposematic method displayed by the blue-ringed is advantageous because the colors iridophores allow it to display are highly noticeable and distinct to predators, especially under the water. All cephalopod’s skin is flexible, but also muscular as well. The surface has a lot of texture, which makes its warning display even more prominent. Compared to other cephalopods that may only use chromatophores or structural reflectors at one time, the blue-ringed octopus can use them both simultaneously resulting in a highly visible warning display. Other methods in cephalopods are very time consuming, while the method observed in this experiment is almost spontaneous. This method may be evolutionarily favorable to both the octopus as well as its predators. This method is beneficial to both the predator and the octopus. Mathger and colleagues suggest that further research be done investigating communication and mating strategies in this species. It would also be interesting to view differences between the flashing mechanism observed in this experiment, compared to other members in the genus Hapalochlaena. Partial display of iridescence may be possible in communicating with other members of its kind, however there is not enough evidence to prove this. This experiment has never been attempted previously, and contains significant information to fuel further research in the area of cephalopod defense strategies. With further research, more information about the blue-ringed octopus and its relatives can be studied. Evolutionary advantages in the role of communication and mating may be observed. No other cephalopods observed have been able to replicate this method of aposematic coloring, and further research may reveal similarities between cephalopods.
In the lab the isopods were observed in a way to where behavior and structures could be properly recorded. The isopods were revealed to two dissimilar scenarios, normal temperature water vs. warm temperature water, to calculate which environment was most preferred. In each distinct scenario ten isopods were placed ten a choice chamber, one side being normal temperature (26.7celsius) and the other being warm temperature (43.3 celsius) , and observed for a total of ten minutes with thirty second intervals which was when we recorded our observations. After observations, it was seen that normal conditions was the most preferred environment by the isopods. In the scenario the Isopods exhibited taxis behavior, which is behavior caused by factors such as light, temperature, water and such. Nothing physical, but rather environmental.
Seaworld is a giant marine life theme park. The greatest attraction to these many theme park would be those killer whales. In fact, these killer whales are the face of the park. As gigant as these mammals are, seaworld is keeping them in some pretty tight quarters. Mr. Jett and Mr.Ventre says “Wild killer whales can swim a hundred miles daily as they socialize, forage, communicate, and breed. In stark contrast, with little horizontal or vertical space in their enclosures, captive orcas swim only limited distances, with most spending many hours surface resting.” The animals don't have the freedom they need. Also when taking the whales out of their natural habit the whales tend to be depressed and not as heath in that situation. They need their freedom in the big ocean blue. Bring them into the small living units, breeding whales in captivity all for the entertainment of humans. At young ages the calves are taken away from their mothers on to a new seaworld park. Mothers of the calves have even been seen denying their offspring.
This research focuses on Gambierdiscus toxicus which is an armored, marine, benthic species in the phylum Dinoflagellata. It has an epitheca and a hypotheca, that is very similar in size, compressed anterio-posteriorly. The theca is covered with numerous deep and dense pores which are very thick. This species is autotrophic creating energy via several golden-brown chloroplasts (Hackett et al 2004), but is also heterotrophic and hence is referred to as mixotrophic. It has a ventrally – oriented crescent shaped nucleus. (Adachi & Fukuyo 1979). It usually inhabits warmer waters such as bay, mediterranian, tropical/sub – tropical in North/Central America (Shiumuzu et al 1982; Loeblich & Indelicato 1986), Asia/Pacific (Holmes & Tao 2002; Lu & Hodgkiss 2004) and has recently been identified in the Mediterranean (Aligizaki & Nikolaidis 2008). These authors identified the organisms to genus level, at best of their effort, so may have been one of the less common members of its genus although it is unlikely.
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Land, M.F.1965. Image formation by a concave reflector in the eye of the scallop, Pecten maximus. J. Physiol. (Lond.) 179: 138 153.
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