Non Chordates

Introduction

The Animal Kingdom, sometimes known as the Kingdom Animalia or the Animal Kingdom is essentially divided into two divisions, namely, Chordates and Non-chordates.

Chordates are the creatures that have a notochord at some point in their lives, which includes humans. Furthermore, non-chordates are creatures that do not possess a notochord throughout any stage of their life cycle.At some point in their lives, chordates develop a cartilaginous string or rod-like structure down the rear of their bodies, known as a notochord (Gr., noton=back, L., chorda=cord).

Non Chordates

Non–chordates are animals that do not have the rod-like structure known as the notochord in their bodies, and are thus classified as such. For the most part, this phylum contains members of the phyla Porifera as well as members of the phyla Echinodermata, Mollusca, Arthropoda (including the worms), Aschelminthes, Platyhelminthes, Ctenophora, and Coelenterata (which includes the worms). They are all believed to be a part of the non-chordates group of individuals.

Some of the general characteristics of the Non Chordates are as follows:

1. They are primarily classified as pseudocoelomate, coelomate, triploblastic, or cylindrical creatures in terms of shape.
2. Normally, their circulatory system is in an open position throughout their body.
3. Fertilization occurs in an endless cycle, but other species have been shown to have internal fertilisation.
4. The process of reproduction involves both sexual and asexual methods of reproduction.
5. The majority of the time, it is impossible to make a precise difference between the genders of the group’s members.
6. It is believed that the non–chordates respire by using their body surface, trachea, or gills to accomplish this task.

Saccoglossus and Balanoglossus are two of the most well-known members of the phylum Saccoglossus.

Invertebrate Chordates

Vertebrata, Urochordata, and Cephalochordata are all extant subphyla of Chordates. All vertebrates are chordates, meaning they have a backbone. The other two subphyla are invertebrate chordates, which are vertebrates without a backbone. The subphylum Urochordatae includes tunicates (also called sea squirts). Lancelets are members of the subphylum Cephalochordata, which includes a variety of other animals. Tunicates and lancelets are both tiny and primitive in appearance. They are most likely related to the first chordates, which appeared more than 500 million years ago and developed into many forms.

Tunicates

Tunicates are thought to number over 3,000 species in the wild (see Figure below). They live in shallow seas. Tunicates are free-swimming throughout their larval stage. They possess all four of the hallmark chordate characteristics (see the “Chordates” concept). Adult tunicates are sessile, meaning they don’t move around. A notochord and post-anal tail have been removed from them.

Adult tunicates have a barrel-shaped body shape. They feature two apertures that allow water to be sucked into and out from the body. The flow of water produces food for the filters, which in turn feed the fish. Tunicates reproduce by sexual reproduction. Each individual is capable of producing both male and female gametes at the same time. They do not, however, allow themselves to be fertilised. Tunicates can also reproduce asexually through the process of budding.

Lancelets

Lancelets are a rare and endangered species, with just around 25 species still alive. They like to live on the ocean floor, where the water is quite shallow. Lancelet larvae are able to swim freely. The adults are capable of swimming, but they prefer to spend their time buried in the sand. Lancelets, like tunicates, feed on the filtrate of the water. Aquatic organisms receive water through their mouths and discharge it through an aperture known as the atriopore (see Figure below). Lancelets reproduce sexually and have distinct male and female reproductive organs.

Invertebrates Non Chordates Examples

Included in the non-chordate group are Porifera, Coelenterata, Ctenophora, Platyhelminthes and Aschelminthes. Non-Chordates are characterised by the following general characteristics: they are cylindrical, triploblastic, coelomate, or pseudocoelomate creatures, and they have no teeth.

Conclusion

Invertebrates are any animals that are not Chordates. Invertebrates account for more than 90 percent of all extant animal species. Their bodies are supported by an elastic rod-like structure known as a notochord, which does not exist in these species. Annelida (non-chordates), Arthropoda (non-chordates), Mollusca (non-chordates), and Hemichordata (non-chordates) are non-chordates. This phylum consists of a small group of worm-like marine animals that are organised at the organ-system level of organisation.