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What Is Phylum In Biology

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Definition Based On Genetic Relation

Chordates – CrashCourse Biology #24

The most important objective measure in the above definitions is the “certain degree” that defines how different organisms need to be members of different phyla. The minimal requirement is that all organisms in a phylum should be clearly more closely related to one another than to any other group. Even this is problematic because the requirement depends on knowledge of organisms’ relationships: as more data become available, particularly from molecular studies, we are better able to determine the relationships between groups. So phyla can be merged or split if it becomes apparent that they are related to one another or not. For example, the bearded worms were described as a new phylum in the middle of the 20th century, but molecular work almost half a century later found them to be a group of annelids, so the phyla were merged ” rel=”nofollow”>family). On the other hand, the highly parasitic phylum Mesozoa was divided into two phyla when it was discovered the Orthonectida are probably deuterostomes and the Rhombozoa protostomes.

This changeability of phyla has led some biologists to call for the concept of a phylum to be abandoned in favour of cladistics, a method in which groups are placed on a “family tree” without any formal ranking of group size.

Kingdom Animalia: Phylum Chordata

The name Chordata comes from the Greek words “Chorde” meaning cord or string and “ata” which means bearing. Therefore, chordates are animals that have a notochord/cord at some point of their lives.

While the majority of animals in the Phylum Chordata have a vertebrate , the group also consists of protochordates which are closely related to vertebrates. While they lack a backbone which is present in all vertebrates, these organisms have a dorsal nerve cord and a notochord and thus qualify to be classified under the Phylum Chordata.

Currently, there are an estimated 65,000 chordate species. While there are not many when compared to some of the other groups, they exhibit great diversity and can be found in a variety of habitats, in aquatic and terrestrial environments, across the world.

Some examples of chordates include:

Kingdom Animalia: Phylum Platyhelminthes

The Phylum Platyhelminthes include organisms known as flatworms. They are dorsoventrally flattened worms and thus lack a coelom. The space between body organs is therefore filled with mesenchyme. Although they have a tissue/organ system level of organization , they lack a circulatory system, a respiratory system, and a true anus.

Like some of the other animals, these organisms are triploblastic and therefore have three embryonic cell layers . They are also bilaterally symmetrical and can, therefore, be divided into two equal halves from head to tail.

While some of the organisms can survive in extreme environmental conditions , the majority of flatworms can be found in aquatic and moist environments.

Some of the organisms that belong to the Phylum Platyhelminthes include:

· Turbellaria

· Trematoda

· Cestoda .

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In Biology What Is A Phylum

In biology, a phylum is a division of organism below kingdom and above class . There are 38 animal phyla, with nine phyla Mollusca, Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Arthropoda, Echinodermata, and Chordata making up the vast majority of all animals. The phyla Arthropoda and Nematoda are the most successful, with the former containing between 1 and 10 million species, and the latter containing between 80,000 and 1 million species. Animal phyla are broadly classified into two groups: deuterostomes and protostomes, distinguished from differences in embryonic development.

Only three new animal phyla have been discovered in the last century, although over ten animals formerly put under other phyla have been recognized as their own phyla. Different phyla have fundamental differences in their body plans, and each make up a monophyletic group, meaning the phylum consists of all the descendants of a common ancestor, and none that aren’t. Biological groups that may consist of numerous phyletic groups, such as worms, are termed polyphyletic. The evolution of biological taxonomy has generally been one of strictly defining one phylum from another based on clearly describable physical differences as well as genetic similarity.

What Are The Phylums In Biology

All Phylum


Animalia and its Seven Phylum

  • The Animal Kingdom contains more than two million known species.
  • The Animal Kingdom contains these seven Phyla: Porifera, Cnidaria, Platyhelminthes, Annelida, Mollusca, Arthropoda, and Chordata.
  • The more common name for the Porifera is the Sponge.
  • Cnidaria.
  • Platyhelminthes.
  • Annelida.

Also, what are the different types of phylum? The different phyla in the classification of animals are as follows:

  • Phylum Porifera.
  • Phylum Echinodermata.

Also to know, how many Phylums are there in biology?

There are approximately 35 animal phyla, 12 plant phyla, and 7 phyla of fungi. The bacteria, including the archaea, are grouped into roughly 34 phyla, although the relationships between these groups are not as well established.

What are the 10 Phylums?

Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Mollusca, Arthropoda, Echinodermata, Chordata”.

  • Porifera.

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What Is A Class Made Up Of

classmade up ofclassmade up ofParazoa: Simple animals without a digestive cavity.

  • Phylum Porifera
  • Phylum Coelenterata Corals & Jellyfish.
  • Phylum Ctenophora

The six Kingdoms are: Archaebacteria, Eubacteria, Fungi, Protista, Plants and Animals.

  • Archaebacteria. Archaebacteria are the most recent addition to the kingdoms of organisms.
  • Eubacteria. Eubacteria are also single-celled bacterial organisms.
  • Fungi.

Kingdom Animalia: Phylum Porifera

The Phylum Porifera consists of some of the earliest known animals. They are commonly found in aquatic environments where they feed by filtering water in order to trap and capture organic material. Organisms like Sponges are filter feeders and have been shown to be capable of catching about 70 percent of suspended bacteria and organic matter in their surroundings.

For the most part, members of this Phylum are basal animals characterized by a cellular level of organization. As such, they lack true tissue given that cells are not organized into tissue systems.

Because they lack true tissues, and thus organ systems, members of the Phylum are generally characterized by an aquiferous system that consists of canal networks and chambers that allow water to flow in and out.

Some organisms that belong to the Phylum Porifera include:

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Main Difference Phylum Vs Division

Phylum and division are two taxonomic levels that are used in the biological classification of organisms. Taxonomy is a branch of biology, which scientifically groups and names organisms based on their characteristics and the evolutionary history. Both phylum and division occur below kingdom and above class. The main difference between phylum and division is that phylum is a classification level of the animal kingdom whereas division is the alternative classification level to the phylum in the kingdom Plantae and Fungi. Sometimes the term division is used as the lower classification level of the kingdom Protista and kingdom Monera. The kingdom Animalia comprises 36 phyla. The kingdom Plantae comprises 12 phyla, and the kingdom Fungi comprises 7 phyla.

Interactions With Other Organisms

Everything About Phylum Group | Biology

The rates of metabolism of Brachiopoda are between one third and one tenth of those of bivalves. While brachiopods were abundant in warm, shallow seas during the Cretaceousperiod, they have been outcompeted by bivalves, and now live mainly in cold and low-light conditions.

Brachiopod shells occasionally show evidence of damage by predators, and sometimes of subsequent repair. Fish and crustaceans seem to find brachiopod flesh distasteful. The fossil record shows that drilling predators like gastropods attacked molluscs and echinoids 10 to 20 times more often than they did brachiopods, suggesting that such predators attacked brachiopods by mistake or when other prey was scarce. In waters where food is scarce, the snail Capulus ungaricus steals food from bivalves, snails, tube worms, and brachiopods.

Among brachiopods only the lingulids have been fished commercially, and only on a very small scale. Brachiopods seldom settle on artificial surfaces, probably because they are vulnerable to pollution. This may make the population of Coptothyrus adamsi useful as a measure of environmental conditions around an oil terminal being built in Russia on the shore of the Sea of Japan.

Cincinnetina meeki

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Kingdom Animalia: Phylum Hemichordata

Members of the Phylum Hemichordata are worm-like invertebrates commonly found in marine environments. Their bodies are divided into three main parts including the proboscis, the collar , and the trunk .

They exhibit bilateral symmetry and thus the body can be divided into two equal halves. Because they share several characteristics with chordates and members of the Phylum Echinodermata, Hemichordates are sometimes considered to be the link between vertebrate and invertebrate animals.

Like some of the other organisms, members of this group have coeloms, but lack properly developed organ systems as those found in most higher animals.

Some of the animals classified under the Phylum Hemichordata include:

Blowing Up The Cambrian Explosion

In reality, phyla are defined by more than body plans. Theyre often considered to be distinctive groups of organisms that arose within a particular stretch of 5 to 20 million years during the early Cambrian Period, which started more than 500 million years ago. The sudden burst of diversity during this time is often referred to as the Cambrian explosion, and as James Valentine, professor emeritus of biology at the University of California, Berkeley, once explained, its thought to have occurred because the lack of animal biodiversity up to that point was unique in the history of life. Some say that abrupt climatological or geological shifts were important, too but whatever the exact trigger, the way that evolution altered species back then was seemingly different from the way it alters them now.

One thing is clear: The phyla didnt all pop into existence at the same time. Cnidarians, for example, had already split into the lineages we recognize as classes before echinoderms came onto the scene. As a 2019 paper in Nature Ecology and Evolution pointed out, there is more divergence between those cnidarian classes which include the Scyphozoa , the Cubozoa , the Anthozoa , and the highly diverse Hydrozoa than between humans and sea urchins.

5W Infographics;for Quanta Magazine

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Reproduction And Life Cycle

Lifespans range from 3 to over 30;years. Adults of most species are of one sex throughout their lives. The gonads are masses of developing gametes , and most species have four gonads, two in each valve. Those of articulates lie in the channels of the mantle lobes, while those of inarticulates lie near the gut. Ripe gametes float into the main coelom and then exit into the mantle cavity via the metanephridia, which open on either side of the mouth. Most species release both ova and sperm into the water, but females of some species keep the embryos in brood chambers until the larvae hatch.

The cell division in the embryo is radial , holoblastic and regulative . While some animals develop the mouth and anus by deepening the blastopore, a “dent” in the surface of the early embryo, the blastopore of brachiopods closes up, and their mouth and anus develop from new openings.

How Many Phyla Are There In The Plant Kingdom

Classification (IB Biology)

Depending on definitions, the animal kingdom Animalia or Metazoa contains approximately 31 phyla; the plant kingdom Plantae contains about 14, and the fungus kingdom Fungi contains about 8 phyla. Current research in phylogenetics is uncovering the relationships between phyla, which are contained in larger clades, like Ecdysozoa and Embryophyta .

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Classification Of Phylum Porifera

Phylum Porifera has three major classes:


  • They live in marine, shallow, and coastal water.
  • Choanocytes appear as conspicuously large cells.
  • They possess a calcareous spicule skeleton build of calcium.
  • The body appears cylindrical that exhibits radial symmetry.
  • The body organization is of asconoid, syconoid, or leuconoid type.
  • Example: Clathrina, Scypha etc.
  • They live in the marine and the deep sea.
  • They comprise a six-rayed siliceous spicule skeleton, build of silicon.
  • The body possesses a cylindrical shape with radial symmetry.
  • They have branched or unbranched canal systems.
  • The canal system is of sycon or leucon type.
  • Example: Euplectella, Hyalonema etc.
  • They live in marine or freshwater.
  • Their body is asymmetrical.
  • The canal system is of leucon type.
  • They comprise spongin skeleton fibres and siliceous spicule skeleton of monoaxon and triaxon type.
  • Example: Spongia, Spongilla, etc.

Kingdom Animalia: Phylum Cnidaria

Also known as Coelenterata, the Phylum Cnidaria consists of organisms that are commonly found in marine environments. However, a few species, like Hydra, can be found in freshwater environments.

While there are many species of the Phylum Cnidaria, they all have a simple body structure that consists of two cellular layers . These layers are separated by the mesoglea which is a non-cellular, gelatinous layer.

Although they are simple organisms, they have true tissues including the epithelial tissue, muscular tissue, and connective tissue, etc. However, they do not have an organ level of organization and are therefore classified in the tissue grade. Because of their general morphology, they have radial symmetry and can, therefore, be divided along several planes.

Some of the species that belong to the Phylum Cnidaria include:

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Nervous System And Senses

The “brain” of adult articulates consists of two ganglia, one above and the other below the oesophagus. Adult inarticulates have only the lower ganglion. From the ganglia and the commissures where they join, nerves run to the lophophore, the mantle lobes and the muscles that operate the valves. The edge of the mantle has probably the greatest concentration of sensors. Although not directly connected to sensory neurons, the mantle’s chaetae probably send tactile signals to receptors in the epidermis of the mantle. Many brachiopods close their valves if shadows appear above them, but the cells responsible for this are unknown. Some brachiopods have statocysts, which detect changes in the animals’ position.

Kingdom Animalia: Phylum Annelida

Phylum Meaning

Members of the Phylum Annelida, known as annelids, are segmented worms found in various habitats, in aquatic and terrestrial environments. While they exhibit significant diversity with regards to the body plan, studies have revealed that the majority of species are coelomate and thus have a body cavity.

They are also characterized by multiple body segments with the first segment consisting of the brain in most of the organisms. The body of these organisms can be divided into three main regions including the prostomium , the trunk which consists of multiple segments, and the pygidium which is the post-segmental region. They also contain several internal organs that make up the digestive system and circulatory system etc.

* Annelids also display bilateral symmetry.

Some of the species that belong to the Phylum Annelida include:

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Diploblastic And Triploblastic Organisation

  • Animals in which the cells are arranged in two embryonic layers, an external ectoderm and an internal endoderm, are called diploblastic animals, e.g., Coelenterates. An undifferentiated layer, mesoglea, is present in between the ectoderm and the endoderm.
  • Those animals in which the developing embryo has a third germinal layer, mesoderm, in between the ectoderm and endoderm, are called triploblastic animals .

Figure: Showing germinal layers : Diploblastic Triploblastic

What Is A Phylum

Phylum refers to a principal taxonomic category of animals, which ranks above class and below kingdom. It is the largest group of scientifically categorized animals. The classification is done based on the internal organization of the body of the organism. Organisms of a particular phylum also share a similar body plan as well as external appearance.

Figure 1: Contribution of each phylum to the total number of animal species

Though the kingdom Animalia consists of 36 phyla, most animals in it belong to nine phyla. Those nine phyla are Porifera, Coelenterata, Platyhelminthes, Aschelmeinthes, Annelida, Arthropoda, Mollusca, Echinodermata, and Chordata.

  • Phylum Porifera: Consists of primitive, salt-water sponges with no nerve cells or muscle cells
  • Phylum Coelenterata: Consists of aquatic, lower animals such as Hydra and jellyfish
  • Phylum Platyhelminthes: Consists of flatworms
  • Phylum Aschelmeinthes: Consists of most of the parasitic roundworms
  • Phylum Annelida: Consists of segmented warms
  • Phylum Arthropoda: The largest phylum, which consists of insects
  • Phylum Mollusca: The second largest phylum, consists of invertebrate mollusks such as snails, clams, scallops, chitons, and oysters.
  • Phylum Echinodermata: Consists of sea stars and sea urchins.
  • Phylum Chordata: Consists of vertebrates, which contain a notochord and paired pharyngeal gills. This phylum contains fish, amphibians, birds, reptiles, and mammals.
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    Different Phylum Under The Kingdom Animalia

    In biology, a Phylum is a taxonomic category/level that ranks below Kingdom but above Class. It’s an important category that groups organisms based on a set of characteristics that set them apart from other organisms.

    In the Kingdom Animalia, animals are divided into a total of eleven Phyla that include:

    How Are Marine Organisms Classified

    #6 #Biology #Class11 Kingdom Phylum Class Order ...

    There are millions of species on Earth, and only a small percentage of them have been discovered and described. Some organisms have evolved along similar paths, although their relationship to each other isn’t always obvious. This evolutionary relationship between organisms is known as the phylogenetic relationship and can be used to categorize organisms.

    Carolus Linnaeus developed a system of classification in the 18th century, which involves giving each organism a scientific name, then placing it in broader and broader categories according to its relationship to other organisms.;In order of broad to specific, these seven categories are Kingdom, Phylum, Class, Order, Family, Genus, and Species.;

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