Phylum Hemichordata

Introduction

If you are a student preparing for their upcoming examinations of class 11th, this topic of Phylum Hemichordata is a topic that you cannot take for granted. If you wish to prepare for the neet examinations in the future, having in-depth knowledge of the complete biology of class 11th and 12th at your fingertips is a must as biology is generally the most scoring part. So, without wasting a single second, let’s start with our topic, Phylum Hemichordata. Hemichordata is partially chordates. They are vermiform, can live solitary or in colonies, and their nervous system is of an infra-epidermal type. Hemichordates are preoral, which means they may or may not have gill slits and are without the typical nephridia. In earlier times, hemichordates were generally regarded as Chordata. Still, after vigorous research conducted by biologists, they noticed that Hemichordata didn’t have characteristics of Chordata and then soon it was started to be considered non-chordate. Nowadays, it has been noticed that Hemichordata have both the characteristics of Chordata and non-Chordata, so now it is regarded as Hemichordata. Let’s understand more in detail.

Hemichordata

It may be considered Chordata because it has characteristics of notochord as well as it also shows the characteristics of stomochord, which relates it to non-Chordata. And thereby, scientists now consider it as Hemichordata having both the features of a Chordata and a non-Chordata. Hemichordata characteristics

Habitat:-

• Hemichordata have similar subphylum characteristics and are considered fossorial animals that happen to be found in the deep underground sea

Shape:-

• Hemichordata are worm-like organisms that are brittle and soft and appear as snakes in size. However, their skin doesn’t resemble snakes. They are also known as Tongue warm, Acorn worm and Bull tongue warm

Germ layer:-

• The germ layer in Hemichordates is called the triploblastic germ layer. It is divided into three sub-parts called ectoderm (outer layer), mesoderm (middle layer) and endoderm (innermost layer)

Symmetry:-

• Hemichordata have a symmetrical body structure as they can have two halves

The body shape of Hemichordata

Hemichordata’s body is mainly divided into the following three components:

Proboscis:-

• A part of the frame, the pinnacle is a trunk-like structure and consists of glomerulus used for excretory function
• The different feature of Proboscis is to dig the burrow on the base of the sea
• There is a hollow structure within the Proboscis known as Stomochord or Buccal diverticulum

Collar:-

• The collar is distinctly muscular and encloses a cavity, the collar coelom. It opens to the outside via a couple of collar pores into the first pair of gill pouches behind
• Below the collar, the chordates have genital wings, then hepatic caeca, which is part of the digestive system and at the end of the frame, the anus is located

The nervous system of the phylum Hemichordata

The apprehensive gadget of hemichordates is similar to the non-chordata kind, which has ganglion, that is, the cell frame of the upper part of the neuron. The ganglion is hooked up to a double solid ventral nerve cord. The nerve cord also carries ganglions that connect each nerve cord collectively. That is why the nerve cord is known as ganglionated.

Sexes:-

• Hemichordata is a unisexual animal, meaning that male and female bodies are needed for reproduction functions

Fertilization:-

• Hemichordata follows the external fertilization approach. The female releases their eggs into the water and the male fertilizes the eggs with their sperm outside of the female body. But in a few species, fertilized eggs develop directly into an adult Hemichordata

Development:-

• Hemichordata follows direct and indirect improvement tactics
• The oblique developmental approach consists of a prolonged pelagic planktotrophic tornaria larva level. Hemichordata exists in a larval degree that feeds on plankton before becoming a grownup worm

Hemichordata examples

• Balanoglossus

• Saccoglossus

• Rhabdopleura

• Atubaria
• Dendrograptus

Conclusion

Hemichordata is solitary worm-shaped marine organisms. They stay in the earlier secreted tubes referred to as burrows on the mattress of the ocean. Usually, they filter out feeders (They can swallow the entirety but can eat most effectively those matters that they want to). However, some species are deposit feeders also. They are normally vermiform, solitary or colonial enterococcus coelomate animals with an intra-epidermal anxious gadget and a preoral without or with gill-slits and without typical nephridia. The body structure of the Hemichordata is Simple and open, with an advanced circulatory system consisting of a dorsal coronary heart and a pair of longitudinal vessels, that is, one dorsal and one ventral. Reproduction is mainly sexual. Sexes are usually separated from gonads one to several pairs.