Sharks are marine animals of the class Cartilaginous fish. Species of this class are known to have a cartilaginous skeleton, gills without an operculum, no swimming bladder, and placoid scales. The class includes many different species, including the White shark, Tiger shark, and smaller catsharks, constituting over 400 species around the world (Florida Museum). Most people have vague ideas about this topic, and it is important to review it properly to educate ourselves on the organisms that make up our ecosystems.
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I chose this topic because I was intrigued by the evolution of sharks and wanted to learn more about them. In fact, they have distinctive features that separate them morphologically from other species of the class, and they are therefore also very special from a biological point of view. By presenting this topic, I will highlight the key characteristics of sharks and share them with other people. Personally, I view sharks as intimidating and frightening due to their appearance, yet I also acknowledge their purpose in the world as living organisms.
The creatures that are considered to be the sharks’ ancestors barely resembled the modern sharks we know today. The first appeared on Earth over 350 million years ago; however, only around 100 million years later did the shark-like fish develop into actual sharks (Davis, n.d.). Although a lot of people are fearful of sharks, most would not attack a human. The whale shark, for example, feeds on plankton only, posing no threat to people. Other sharks, such as the mako, prefer rods or reels. It is a common misconception to assume that sharks are human predators despite their sizes.
These animals are quite highly developed in comparison to the other orders of the class Cartilaginous. This can be seen in their mating and offspring-carrying behavior: the females only breed once in 3 years and give birth to fewer organisms than bony fish (Prince 4). In biological terms, the significance is determined through the number of healthy sharks that will have a higher chance of survival than the many eggs of bony fish, as well as through the shark’s ability to give live birth (similarly to the well-developed mammals). Their sensory system is also an adaptation to the often fierce competitive environment: through electroreception, they are able to detect their prey, first locating it through the olfactory system. As their sensitivity to water temperature is also exceptional, they prefer warmer water (Prince 7). Unfortunately, overfishing is becoming a serious issue: thousands of species are illegally being killed each year, with the trend reaching its peak in the 21st century. Saving these animals is the least we can do to help restore natural balance. While I personally have a fear of sharks, their importance to the ocean’s ecosystem, and by extent, to the environments we as people inhabit, cannot be understated.
In conclusion, sharks are a crucial part of the marine ecosystem, skillful predators with well-developed sensory systems. Although shark attacks occasionally happen in their natural environment, most species are harmless to humans. They have been living on Earth for over 100 million years and, in that time, have adapted to the slightly altering conditions of the aquatic world. Hopefully, this presentation provided better insight into the unfamiliar life cycle of sharks, as well as their superior characteristics compared to other fish. Personally, I have learned a lot about their evolution and structure by working on this presentation. Unfortunately, due to the warning decrease in the number of species because of overkilling, we must find ways to protect sharks from becoming endangered.
Davis, Josh. “Shark evolution: a 450 million year timeline.” Natural History Museum, Web.
Florida Museum. “Sharks species profiles.” Florida Museum, Web.
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Prince, Diana. Book of sharks. AuthorHouse, 2018.