Chordates and Non-Chordates
Have you ever wondered what makes an animal a chordate? Chordates include animals ranging from fish to mammals, but all share four defining characteristics.
These characteristics include a notochord, pharyngeal slits, dorsal nerve cord, and post-anal tail. In this article, we’ll delve into the world of chordates and non-chordates, looking at their key features and subphyla.
Four Main Features of Chordates
As we mentioned earlier, there are four main features of chordates. The first of these is a notochord, which is a flexible, rod-like structure that extends down the animal’s body and helps to provide support and structure.
In most chordates, the notochord is replaced by the vertebral column (or spine) during development. The second feature of chordates is pharyngeal slits, which are openings in the throat region.
These slits are initially used for feeding and breathing but can serve different functions in different animals. For example, in fish, gills develop from these slits, while in humans, they contribute to the development of different head and neck structures.
The third feature is the dorsal nerve cord, which is essentially the animal’s spinal cord. This cord runs along the back of the animal and connects to the brain.
In vertebrates (animals with a backbone), the cord is protected by the vertebral column, while this is not the case for non-vertebrates. Finally, chordates have a post-anal tail, which is essentially an extension of the animal’s body beyond the anus.
In some chordates, this tail disappears during development, while in others, such as fish and amphibians, the tail remains throughout the animal’s life.
Subphyla of Chordates
There are three subphyla of chordates: Vertebrata, Cephalochordata, and Urochordata. Vertebrates are animals with a spine, which includes everything from fish to birds to humans.
These animals have a well-developed brain and sense organs, as well as specialized respiratory and circulatory systems. The other two subphyla of chordates are both non-vertebrates.
Cephalochordata consists of animals known as lancelets, which are small, slender, fish-like creatures that live in sandy ocean bottoms. Lancelets have a notochord that runs the length of their body and many other features typical of chordates.
Finally, Urochordata includes creatures that are often known as sea squirts or tunicates. These animals are filter feeders that are said to resemble bags or tubes, due to their hollow bodies.
In the larval stage, these animals have all four features of chordates, but as they develop, they tend to lose many of these features.
Phyla of Non-Chordates
Chordates are just one of the many animal phyla, and non-chordates make up the majority of animal life on Earth. These phyla include Porifera (sponges), Cnidaria (jellies and coral), Platyhelminthes (flatworms), Nematoda (roundworms), Annelida (segmented worms), Mollusca (snails, octopuses, and squid), Arthropoda (insects, spiders, and crustaceans), and Echinodermata (sea stars and urchins).
These non-chordate animals can have a wide variety of features that allow them to survive and thrive in different environments. For example, some animals like sponges are immobile and feed on small particles of food that drift by them.
On the other hand, animals like insects have evolved complex structures and behaviors that enable them to fly, mate, and communicate with each other. However, despite their differences, all non-chordate animals share some common features, including the absence of a notochord, dorsal nerve cord, and post-anal tail.
Conclusion
In conclusion, chordates are animals that are defined by four main features: notochord, pharyngeal slits, dorsal nerve cord, and post-anal tail. The subphyla of chordates include Vertebrata, Cephalochordata, and Urochordata, and these animals range from fish to humans.
Non-chordates make up the majority of animal life on Earth and have a wide variety of features that allow them to survive and thrive in different environments. By understanding the differences and similarities between chordates and non-chordates, we can better appreciate the incredible diversity of animal life that exists on our planet.
What are Non-Chordates? While chordates are defined by specific features that set them apart from other animals, there is an incredible diversity of animal life outside this group.
These non-chordate animals are found throughout the world’s oceans, freshwater habitats, and on land, representing a wide array of body shapes, structures, and behavior.
Phyla of Non-Chordates
Non-chordate animals belong to a range of phyla, including Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Mollusca, Arthropoda, and Echinodermata. Porifera are better known as sponges and are the simplest of all the animal phyla.
They are sessile creatures that attach themselves to the ocean floor or other substrates, and they feed by filtering small particles from the water. Cnidaria includes animals like jellyfish, coral, and sea anemones.
These animals have radial symmetry and tentacles surrounding a central mouth, which they use to capture prey. Some species of Cnidaria are capable of stinging their prey or predators.
Flatworms belong to the phylum Platyhelminthes and are usually free-living in aquatic or moist terrestrial environments. Some species, however, are parasitic, inhabiting the bodies of other animals and feeding on their tissues.
Nematodes, also known as roundworms, are abundant and can be found in soil, fresh, and saltwater, as well as in the bodies of other animals. Some species are harmful, causing diseases in humans, while others are beneficial, such as those used in organic gardening as natural pest control.
The phylum Annelida includes segmented worms like earthworms, leeches, and marine worms. These animals typically have a distinct head and body segments, with much of the body made up of repeating segments.
Mollusks are soft-bodied animals that include a wide range of species, such as snails, squid, and clams. These animals have a muscular foot used for movement, a visceral mass containing their organs, and a mantle that produces their shell.
Arthropods are the largest animal phylum, consisting of animals like insects, spiders, crabs, and centipedes. These animals have an exoskeleton, jointed appendages, and segmented bodies.
Arthropods play an important role in many ecosystems, and their success has been attributed to their adaptability and diversity. Finally, Echinoderms include sea stars, urchins, and sand dollars.
These animals have a spiny exoskeleton and a unique water vascular system that helps them move, eat, and breathe. Similarities Between
Chordates and Non-Chordates
Despite the many differences between chordates and non-chordates, there are some basic characteristics that are shared by both groups.
For instance, all chordates and non-chordates are multicellular, meaning they are composed of many cells, each performing a specialized function. Both groups also have nerve cords, which are bundles of nerve fibers that transmit signals throughout the body.
In chordates, the dorsal nerve cord runs along the back of the animal and is protected by the vertebral column. In non-chordates, there may be a variety of arrangements, such as a diffuse nerve net in cnidarians or a ganglionated ventral nerve cord in arthropods.
Conclusion
The world of non-chordate animals may seem vast and endless, but it’s important to remember that even with all their differences from chordates, there are still similarities that connect us all. As we learn more about the incredible diversity of animal life on our planet, we can better appreciate the natural wonders around us.
Side by Side Comparison: Chordates vs Non-Chordates in Tabular Form
Characteristics | Chordates | Non-Chordates
— | — | —
Notochord | Present at some point in development | Absent
Nerve Cord | Dorsal nerve cord protected by vertebral column | Varies, may be diffuse nerve net or ganglionated cord
Pharyngeal Slits | Present at some point in development, may develop into gills or other structures | Absent or modified for different functions
Post-anal tail | Present at some point in development or throughout life | Absent
Respiratory Pigments | Present in most species | Absent or present in a modified form
Excretory Organs | Kidneys or different types of excretory structures | Varied, may be absent or simple tubules
Comparison of Characteristics
Chordates and non-chordates are two distinct groups of animals, each with unique features that set them apart. A side-by-side comparison of these characteristics can highlight the main differences:
Notochord: Chordates have a notochord at some point in development, which provides support and structure, while non-chordates lack this flexible, rod-like structure.
Nerve Cord: Chordates have a dorsal nerve cord protected by the vertebral column, while the nerve cord in non-chordates varies depending on the species. Some animals, like cnidarians, have a diffuse nerve net, while arthropods have a ganglionated ventral nerve cord.
Pharyngeal Slits: These slits are present at some point in development for chordates and may develop into gills or other structures, while they are absent or modified for different functions in non-chordates. Post-anal Tail: Chordates have a post-anal tail at some point in development, which can remain throughout their life, whereas non-chordates lack this feature altogether.
Respiratory Pigments: Most chordates have respiratory pigments like hemoglobin or myoglobin to transport oxygen, while non-chordates either lack respiratory pigments or have modified versions for different functions. Excretory Organs: Chordates have kidneys or other specialized excretory structures, while non-chordates may have simpler tubules or lack excretory organs altogether.
Summary
In summary, chordates and non-chordates are two distinct groups of animals that share some similarities, such as being multicellular and having some form of a nerve cord. However, their differences are what set them apart.
Chordates have unique features like the notochord, pharyngeal slits, dorsal nerve cord, and post-anal tail, while non-chordates have their own distinct characteristics. By comparing the differences and similarities between chordates and non-chordates, we can gain a better understanding of the incredible diversity of animal life on our planet.
In conclusion, the world of animals is incredibly diverse, with chordates and non-chordates representing two major groups that share some similarities but also have unique differences. Chordates are characterized by the notochord, pharyngeal slits, dorsal nerve cord, and post-anal tail, while non-chordates lack these features.
Both groups share some basic characteristics, including being multicellular and having some form of a nerve cord. By understanding the differences and similarities between chordates and non-chordates, we can better appreciate the variety of animal life on Earth and foster a greater understanding of our natural world.