You have found the perfect spot if you are interested in learning the general characteristics of cephalochordata, since our goal here is to provide you with some fundamental information on cephalochordata.
One of the most iconic species in all of zoology, the lancet Branchiostoma sp., more often referred to as Amphioxus, is part of the class of animals known as Cephalochordata.
Cephalocordates are most commonly discovered on sandy beaches in southern seas, where they burrow into the sand with their front end exposed to the environment. Approximately 28 different species have been identified. They are able to swim by making their bodies move in a smooth, lateral motion.
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What are the general Characteristics of Cephalochordata?
The amphioxus is particularly fascinating from a zoological point of view since it illustrates the four main characteristics of chordates in a simplified design, and on the other hand, it may be regarded an archetype of the phylum. This makes the amphioxus a very intriguing animal.
If we want to talk about the general characteristics of cephalochordata, we should consider the size of these amazing animal:
It measures between 5 and 7 centimeters in length and has a body that is slim, laterally compressed, and translucent.
It functions as a filter: water enters through the mouth, where it is moved along by cilia in the oral cavity; it then travels through many gill slits on both sides of the pharynx before entering the atrial cavity. It leaves the body by way of the pore that’s found in the atrial cavity’s wall.
Mucus is produced in a groove in the floor of the throat known as the endostyle, and it is transported to the gill slits by cilia. Food particles in the water are able to flow through the clefts, where they are then captured by the mucus and transported into the gut. The meal particles are then transported into the hepatic caecae, where they are digested, and the mucus is removed from the food particles.
Circulation System of Cephalochordates
Another important piece information about the general characteristics of cephalochordata is the closed circulation system of cephalochordates.
The mechanism of closed circulation is rather complicated. Although there is no heart, the circulatory pattern is comparable to that of fish. After traveling through the dorsal aorta to the back of the body, the blood then travels through the microcirculation system to all of the body’s different tissues before being collected by the veins.
These tubes empty into a ventral aorta, which uses peristaltic contractions of the artery wall to propel the blood forward through the body. After traveling via the gill vessels and the gill bars, where it is oxygenated, the blood finally reaches the dorsal aorta.
Other general Characteristics of Cephalochordates
The nervous system is organized around a hollow dorsal nerve cord that is positioned above the notochord. Text centers the neural system. The collagen sheath that surrounds the nerve cord serves as a protective barrier, similar to how vertebrae in fish serve to shield the spinal cord from injury.
On of the most interesting general characteristics of cephalochordata is that there is no evidence of a brain.
Each of the two sexes, which are distinct from one another, have 25 pairs of gonads, which are found in the wall of the atrial cavity. The process of fertilization takes place after the cells have been discharged into the atrial cavity and have passed through the atriopore. The egg will hatch into a larva not long after it has been laid, and the larva will progressively develop into the adult form.
The amphioxus is the only other chordate that so vividly exemplifies the fundamental traits shared by all chordates. Not only does it have the four main characteristics of chordates, which are the dorsal nerve cord, the notochord, the pharyngeal-branchial clefts, and the post-anal tail, but it also displays secondary characteristics, such as a hepatic diverticulum or the beginning of a ventral heart.
In contrast to invertebrates, in which the musculature has the same thickness all around the body cavity, it is indicative that the thickness of the dorsal region of the muscle layer is larger than that of the ventral half.
There is a school of thought among zoologists that Amphioxus is a living descendent of an ancestor that was the progenitor of both cephalochordates and vertebrates. As a result, according to the cladistic classification system, the cephalochordates are the vertebrates’ sister group and share the general characteristics of cephalochordata.
