Evolution can be defined as a developing process, where an animal or plant gradually becomes a more advance and multifaceted form. Examples of evolution include natural selection and mutations. Throughout history our planet and the species found on it were required to evolve to survive. Thus, leaving the best possible forms to survive and thrive throughout history. This process took time and has produced many variations, but the common result is species that became enhanced. There are many different aspects that have evolved, however the skin is the main focus.
Beginning an exploration of the epidermis of both aquatic and land animals requires knowledge of the different types of dermis, be it plates, slime, scales, or hair. Foremost the plates
The body covering or epidermis of this species is scales. These scales evolved from the “dermal armor covering the body of ancient vertebrates,” similar to the Placoderms mentioned above (Sharpe 2001) Bony fish scales are composed of dermal elements that potentially contains dentine and enamel protein, but do not contain keratin (Sharpe 2001). There are a few different types of scales Osteichthyes may have such as cosmoid, ganoid, cycloid and ctenoid also known as elasmoid. Both the cosmoid and the ganoid scales are more common on ancient fish, and are larger in size, used for protective measures, and are multilayered. The Teleost fish scales include the scales of modern fish that being cycloid a circular scale and ctenoid a sharper more rigid scale. “Teleost scales have excellent hydrodynamic properties and provide a protective layer resisting penetration” allowing bony fish to be more agile when swimming (Zhu et. al 2012). Thus in combination with the lateral line, the newly evolved scales allows bony fish to anticipate a predator, and have a better chance of
1. Accessed November 28, 2015. http://www.athenapub.com/17Records-09.htm.
Sharpe, Paul T. "Fish Scale Development: Hair Today, Teeth and Scales Yesterday?" Current Biology 11, no. 18 (2001): R751-752. Accessed November 28, 2015. http://www.sciencedirect.com/science/article/pii/S0960982201004389.
Zhu, D., Ortega, C.F., Motamedi, R., Szewciw, L., Vernerey, F., Barthelat, F., 2012. Structure and mechanical performance of a modern fish scale. Advanced Engineering Materials 14, B185–B194.
"Differences between Sharks and Bony Fish: More than Just the Skeleton." Shark Savers. Accessed November 29, 2015. http://www.sharksavers.org/en/education/biology/differences-between-sharks-and-bony-fish-more-than-just-a-skeleton/.
"Feather Evolution." Avian Biology. Accessed November 29, 2015. http://people.eku.edu/ritchisong/feather_evolution.htm.
Bergman, Jerry. "CRSQ Abstracts, 2014, Volume 50, Number 3 (Winter)." Why Mammal Body Hair Is an Evolutionary Enigma. March 1, 2004. Accessed November 30, 2015.
Pachycephalosaurians, thick-skulled dinosaurs such as the Stegoceras and the Pachycephalosaurus. (1) Ceratopsians and Pachycephalosaurs are closely related in their characteristics. Ceratopsians processed a saddle-shaped boney frill that extended from the skull to the neck and typically had horns over the nose and eyes. The most popular was the triceratops, which could reach over 26 feet and weigh in excess of twelve metric tons. Their frills served two major functions.
gorillas and the ancestors of humans and chimpanzees) (Reed, 2007). The ‘recent host switch’ hypothesis, would explain the genetic similarities between the lice acquired by modern humans and the lice acquired by gorillas, chimps, and other primates (Reed, 2007). Because of the evidence of these genetic similarities and differences in Pediculus and Pthirus, the evolutionary divergence of humans, gorillas, and chimps appears to be directly correlated with the evolutionary divergence of different species of lice (Reed, 2007). This evidence allows us to conclude that in order for modern human head lice to have evolved from its ancestral form, humans first had to evolve into a less hairy, less neanderthalian versions of themselves. The evolved trait for hairlessness, then, must have occurred through some form of natural selection. Who would have thought that head lice, the natural enemy and nightmare of second-graders and their parents, could be the key to unlocking the--quite literal--naked
Biology: The average length of a Skipjack Tuna is 32 inches long (80cm) and weigh anywhere between 7-22 pounds (8-10kg). The current record for the biggest Skipjack Tuna weighs in at 76 pounds (34.5kg) and was 43 inches long (108cm). The colour of the top region is either dark blue or purple, and the lower region including the belly are primarily a silver colour with anywhere from 4-6 dark, broken lines that run across the body (FLMNH). The body shape is elongated and possesses a fusiform shape, meaning it is wide in the middle and tapers at both ends; it also possesses a bilateral symmetry. There are two dorsal fins present, the first consisting of around 14-16 spines. There is a small gap in between the two fins, and the second fin is spineless (ADW) (FLMNH). Behind the second dorsal fin, are between 7-9 finlets, which aid the fish in “reducing turbulence and maintaining directional control when swimming at high speeds” (Gardieff, Susie). On the underlying side of the Tuna, the anal fin is present and it is in about the same location below the second dorsal fin, and following the anal fin is another 7-8 finlets. The fish has short pectoral fins consisting of between 26-27 rays. The fish also have a single row of teeth, shaped conically (cone shaped) (FLMNH).
Scorpaenidae are mostly marine fish,very few found in fresh and brackish water. The family have around around 45 different genera and 380 different species. They are mostly found in the India Ocean and the Pacific Ocean. Most of them lives in coral, tropical reefs and shallow waters, warmer areas. Not all of the family fish lives in the shallow water, small portion of the Scorpaenidae live deep as around 7,000 feet. Just like most of the coral reef fish are, Scorpaenidae have camouflaged body. Their characteristic reflects their name, they have sharp spine that can sting other organisms. Their spine are covered with venomous mucus just like how some other kind of fish are covered with the venomous mucus. Their body are covered with scales. Generally speaking, the Scorpaenidae family fish have different number of spines over the course of the body. Most known type pf Scorpaenidae are lionfish and scorpionfish. Lionfish have preorbital bone with 3 spines, spines and third below the diagonal; , big mouth, end position, oblique fissure. Mandible, vomer and jaw bone with villiform teeth group. Gill openings are wide, tetrabranchiate membranes without the isthmus, pre-opercular margin with 5 spines. Body are ctenoid scales, round head. On the side, there are about eight to nine dorsal fin, fin spines and rays of an anal fin; five to six pectoral fins, they are large, round, and are branched from the upper fin rays. There are about one to five pelvic, sub thoracic; caudal fin rounded truncate. Reef stonefish are extremely camouflaged, they could look exactly like a rock when hiding for predation. The spines of Scorpaenidae are hard and rough, some of their fin spines have poison, can cause serious pain, swells and fatal wounds. Some of ...
The background of this article gives information that is necessary to understand the experiment. The shape of the pelvic girdle is an appropriate predictor of both phylogeny and movement in terrestrial vertebrates. However, in marine vertebrates, the gravitational forces typically applied to terrestrial pelvic girdles are not there and therefore have little impact on the shape of the girdle. Pelvic girdles of fish are generally not attached to the vertebrae and primarily are used as a place for muscles to attach and supporting of the fins. The authors discuss how in many cases the pelvic girdle could be removed and not result in any complications. However, there are some marine vertebrates that are capable of bottom walking on the ocean floor with their fins. In batoids, the pelvic fins are used for walking, which is when pelvic fins move in an alternating fashion, or punting, when both pelvic fins move at the same time. There is also augmented punting; this is when the vertebrate uses both the pectoral fins and the pelvic fins to generate more thrust, this action decreases the forces on the pelvic fins during a punt. While this locomotion would
In conclusion, the question of how hair texture among an ethnicity is determined has yet to be answered. However, new developments such as the evidence that all humans have the same single origin in Africa and mutations in the P2RY5 gene can determine the hair texture of a human, have shown that researchers are quite close in determining the hair texture of an ethnicity. These developments have the possibility of leading to new hair removal and hair growth treatments. The future looks bright for hair research and hopefully in the next 20-50 years the question is answered.
What is evolution? Evolution in modern terms is fairly easy to understand. Evolution is the theory that life on earth began with a single celled organism that lived more that 3.5 billion years ago that slowly evolved into many diverse creatures over time. When you break down this theory into sections you get 6 factors: evolution, gradualism, speciation, common ancestry, natural selection and nonselective mechanisms of evolutionary change.
Acanthaster planci, commonly known as the crown-of-thorns starfish, is an echinoderm that has attracted much attention and has been the focus of much research over the past few decades. Although the starfish has interesting physic...
This tree is an Eastern White Pine and it took me 4 steps to get the answer.
Work Cited Colby, Chris. A. Web. " An Introduction to Evolutionary Biology." 28 August 2015.
Sharks are known for their ability to kill and their teeth, but what people don’t pay much attention to, is their skin. A shark’s skin has, “sleek scales that resemble tiny teeth and are made of a tough material called dentin” (Lewis, Tanya. “Biomimetics: 7 clever technologies inspired by nature.” Live Science. Purch. 22 Apr. 2013. Web). Not only is the skin durable, but it contains hundreds of tiny teeth throughout the skin that acts
The Axolotl, a crucially endangered neotenous species of mole salamander, has adapted to fit its environment so it can easily catch food and evade predators. The Axolotl’s habitat is the lake system of Xochimilco that is near Mexico City, Mexico. This shallow, fresh water lake complex has a temperature range of 6- 20°C and a pH of 7- 12. The complex also has the Axolotl’s primary food sources of mollusk, insect larvae, and other crustaceans. However, with the introduction of foreign species such as the Asian Carp and the African Tilapia, the Axolotl now has predators that may eat and threaten it, and it has competition for the animals it usually eats. Fortunately, the Axolotl has developed adaptations that aid it in catching food and evading predators. To help it catch food the Axolotl’s teeth are shaped like cones, so that its “vacuum” action of sucking in as much water in order to also eat food is aided by the shape of the teeth, which allow it to grip, rather than chew. To aid them in avoiding predators they are able to metamorphose so that they use their lungs more than their gill, which allows them to leave very toxic waters and the predators within. Another adaption that helps them deflect any predator is that they are able to regenerate body parts that have been lost, allowing them to stay as strong as possible. Axolotl’s have adaptations that aid their survival from predators in the lake complex Xochimilco that they reside in.
The overfishing for shark fins has decimated certain species and endangered other species of sharks. Sharks have existed for thousands of years. Scientists have proved that ancestors of today’s shark species existed during the age of the dinosaurs. Sharks have resisted extinction for so long because of natural selection, but since the new delicacy of shark fin soup has become popular in mostly Asian countries they might not resist extinction for much longer. Sharks are extremely vulnerable creatures, despite their frightening amount of teeth. While it takes humans on average thirteen years to reach sexual maturity, it takes sharks up to 20 years and they produce very few offs...
When facing a hungry hunter the ballfish rapidly swallow around 35 gulps of water in the course of 14seconds which are then pumped into stomach. Biologist at the University of Massachusetts at Amherst, Elizabeth Brainerd, has recently shown that a pufferfish’s stomach is a perfect water ballon. As water pours into it, the stomach expands up to 100 times its normal volume. Pufferfish skin is also set for ballooning. It is made of wavy fibres that straighten out as the fish inflates. When the skin expands the fish’s tail and fins immerse into skin, forming a nearly perfect sphere (balloon). When the wavy fibres finally pull tight, they become hard, giving the pufferfish a tough shell that protect from predators, giving them a hard time to penetrating. Some species have spines normally hiding in these skin fibres, but when skin is tighten spines flip up. When fish gets bigger it gives a signal to predator “don’t come closer I’m not so small as you thought”.
The increase in brain size may be related to changes in hominine behavior (See figure 3). The third major trend in hominine development is the gradual decrease in the size of the face and teeth. According to the Microsoft Encarta Encyclopedia ’98, the fossil evidence for direct ancestors of modern humans is divided into the category Australopithecus and Homo, and begins about 5 million years ago (See figure 1). Between 7 and 20 million years ago, primitive apelike animals were widely distributed on the African and, later, on the Eurasian continents (See figure 2). Although many fossil bones and teeth have been found, the way of life of these creatures, and their evolutionary relationships to the living apes and humans, remain matters of active discussion among scientists.