Fish is a common name given to a selected group of vertebrates. The origin of fish has many different viewpoints. The only thing we are sure of is that prokaryotes were here on earth first. This leads us to the hypothesis that all organisms are more elaborate versions of each other and prokaryotic organisms. Fish are known to be the stepping stone for all tetrapods (all vertebrates that walk on land) and are also considered the first known vertebrates. Fish are ever-changing creatures over the past 300 years their dimensions, physical features and their ability to adapt has caused them to be the most common vertebrate. The evolution of fish has controlled the waters for many years we may never know all the species that once existed. However, …show more content…
They have come in several forms and also with the ability to take in vast chunks of food. The evolution of fish mostly occurred in the period of five million years and three and a half million years ago. These periods are known as the Silurian and Devonian periods with the Devonian period being commonly known as the age of fishes. The Ostrocoderms was a group of fish that evolved before the Silurian period. These fish have always been described as small fish that had crests on their round heads with an array of spines. The Ostrocoderms are currently extinct. The Silurian period saw the diversification of the Aganthan fish commonly known as the jawless fish. The Agnathans were the first vertebrates and lived during the period five hundred and ten million and three hundred and fifty million years ago. As they evolved, the jawless fish became more streamlined and had heads that were dorsoventrally …show more content…
They also had a spine, that was dorsally bony, that aided in balancing during their movements. The jawless fish had circular mouth parts that supported in sucking or even filter feeding (Larson, Echelle, & Kornfield, 1985). These features though are found in the present hagfishes and lampreys. An example of the Agnathans was the hemicyclasis, a fish that had just one nostril and a head shield that was bony. During the Devonian period, the Agnathans evolved, and fish with paired fins surfaced. These fish had some similarities to the Agnathans as they had a flexible tail that aided in propulsion and also had a head shield that was plated. Some of the fish with paired fins have small eyes that firmly set together above the head shield. They also have sensitive areas on every side of the head shields and these areas are covered with incredibly tiny bony plates. These organs acted as pressure sensors in water that was murky even though it his suggested that just like sharks, they sensed electrical
Around 144 million years ago, began the emergence of the Ornithischian dinosaurs during the cretaceous period and diversified into North America and Asia.
In this entertaining, search into global fish hatcheries, New York Times writer Paul Greenberg investigates our historical connection with the ever changing ocean and the wild fish within it. In the beginning of the book Paul is telling his childhood fishing stories to his friends, that night Paul discovers that that four fish dominate the world’s seafood markets in which are salmon, tuna, cod, and bass. He tries to figure out why this is and the only logical answer he could come up with is that four epochal shifts caused theses wild fish population to diminish. History shows that four epochal shifts happen within fifteen years causing certain fish species populations to diminish. He discovers for each of the four fish why this happened to
very sickle shaped dorsal fin. Even though the blue whale is large and seems easy to document,
The formation and breakup of continents, mountains, volcanic activity, changes in climate and sea level affected the course of evolution.. Paleozoic Era was restricted to the oceans. Organisms evolved a lot crating the “Cambrian Explosion”.
The concept of transitional species is an important and complex notion in evolutionary biology. To begin with, there is no such thing as transitional species since all living things were always evolving in the past, not stopping at one stage or another, and they will continue to evolve in the future. In terms of evolutionary biology, we use the concept of transitional species as a way to dim ambiguity. Much like the use of the Linnean taxonomic system of species, we come up with concepts like transitional species to organize and classify species in order to understand their evolutionary roots and how those species changed through life’s history to become what they are today. “In the same way that the concept of species can be provisionally meaningful to describe organisms at a single point in time, the concept of transitional species can be provisionally meaningful to describe organisms over a length of time, usually quite a long time, such as hundreds of thousands or millions of years” (111). Though it can be difficult to distinguish what can be considered an ancestral species from another, the fossil record can show us how species change through time as they develop ways to adapt to stresses found in their environments. “In the modern sense, organisms or fossils that show intermediate stages between ancestral and that of the current state are referred to as transitional species” (222). The concept of transitional species is, in essence, fairly straight forward. This paper will outline the concept of transitional (or sometimes termed intermediate) species and the latter’s role in evolutionary biology, as well as go in depth about several common transitional species: Tiktaalik, an animal at the cusp between life in the water and ...
Fish fins developed around 500 million years ago. A fin is a thin appendage attached to the body of an organism that causes either propulsion, stabilization, or the ability to steer and brake. The median caudal, dorsal, and anal fins are possessed by most fish species. The rainbow trout has six different types of fins- an anal fin, an adipose fin, a dorsal fin, a caudal fin, a pair of pelvic fins, and a pair of pectoral fins.
The main idea of this story Fish Cheeks was understanding and appreciation and having pride in one own unique culture. Tan mother invites the minsters family who happens to be her crush at the time who is Robert the minister’s son. Tan felt despaired during the entire evening, feeling ashamed of her family and non- American ways at dinner. At the end of the evening Tan’s mother tells her that she understands that she wants to like all the other American girls and handed a gift. Tan’s mother points out to her that she must not be ashamed of her difference, however, embrace these differences that she has found shame in. Overall the main idea was the differences that we are often ashamed of are the differences we should take pride in, because
Mojetta wrote about prehistoric sharks, and the history of these creatures. According to Angelo Mojetta, author of Sharks, Cladoselache genus, one of the first prehistoric sharks, was buried in sediment that kept it preserved. Unlike other sharks, Cladoselache genus had a circle of tiny plates around it’s eyes for protection against it’s victim’s attempts to fight back. These sharks lived over 400 million years ago. Sharks of the past could mostly be identified by their teeth, because shark’s bodies are made of cartilage. Another shark that was focused on was called, Stethacanthus. This shark had a very unique look. Stethacanthus had a brush like decoration on the top of it’s head, and an extra fin like part that had the same bristle like decorations on it. These characteristics were thought to be used as suction cups, to hitch rides from larger fish. One of the most famous sharks that looks like an over...
Acanthostega had a fish-like tail and gills for breathing under water, this being the aquatic part of it. But at the ends of the arms were “peddle-shaped” appendages, thought to be the first “hands” on Earth. Clack’s discovery proved that some fish had arms and legs in the water. It showed that arms and legs were already evolved before organisms started actually living on land, they were used more for survival than walking. In a sense, the “blueprints” of an arm were already in place.
The discoverer of the titanic, Dr Robert Ballard famously referred to the deep sea as ‘far more alien than going to mars or the moon.’ The deep sea is one of the largest virtually unexplored ecosystems on the planet; it is found at a depth of 1000 fathoms [1] and is subject to adverse changes in temperature, pressure and light penetration amongst other factors. Therefore as expected fish decrease in abundance, and species diversity. This trend is prominent as in order to survive the harsh conditions of the deep sea, fish need a number of specific adaptations. Allowing them to ultimately survive, feed, and reproduce.
A whole lot of hypotheses have been used to explain the quick expansion of animal species in the early Cambrian period about from about 541.0 million to about 485.4 million years ago. The most modern explanations for the Cambrian explosion takes pieces of a lot of these hypotheses and melds them together; incorporating genetic, ecologic, abiotic conditions that set the evolutionary wheel in motion. The current state of understanding the Cambrian explosion still remains a topic of open and exciting debate. The processes in the hypotheses can be stand-alone or very tightly interconnected and mutually supporting of another. One can say the complexity of modern Animalia can be attributed to the complexity of the processes that happened during the rapid diversification attributed from an interaction of biotic and abiotic processes in the Cambrian period.
The morphology of whale sharks is mostly similar to aquatic fish species, but many specific traits help differentiate them from the rest. Whale sharks are the largest fish in the world and can reach a size of around 20 meters (Martins, C., and C. Knickle). This is often compared to the size of a school bus. The shark has a very large transverse mouth. They have 5 very large gill slits and have a larger first dorsal fin compared to the second one (Whale Shark). They have a distinctive spotted “checkerboard” pattern with stripes (Martins, C., and C. Knickle). It is not exactly known why they have this specific body marking. It is believed that the body markings act as a camouflage. The strange thing about whale sharks is that they have 300 rows of teeth that play no role in feeding (Martins, C., and C. Knickle).
These creatures lived in nearshore marine habitats. The next evolution, the Dorudon, showed the evolution of the whale’s spine. Instead of moving from side to side the spine now moved up and down, allowing the creature to swim more effortlessly and efficiently. This creature now more closely resembled the whale but still had teeth for consuming fish that would later evolve and disappear.
The Paleozoic era was some place around 542 million years back to 251 million years prior, otherwise called the timeframe when the supercontinent, Pangea, was still around. The Paleozoic time started with the Cambrian Period (lasted 53 million years). Amid this period there was the "Cambrian explosion" which introduced the Earth to arthropods (considered the ancestors of today's insects and crustaceans) and chordates (animals that have a notochord). This evolution created the colonization of the first creatures with vertebrates to walk among the Earth. After the Cambrian Period came the Ordovician Period (lasted 45 million years).
The world we live in today is full of an exceptional variety of animals. The time it took to conclude to the various sorts of species seen today has been throughout a period of millions of years. The vast majority of these animals are accredited to evolutionary advancements. When the environment changes, organisms have become accustomed to changing to fit their environment, to ensure their species does not die off. These physical changes have resulted in different phyla, ranging from basic structures, like sponges to advance systems, like that of an octopus.