Question

Hepatic portal system has evolved in protochordates
(a) Hemichordates
(b) Urochordates
(c) Cephalochordates
(d) All of the above

Answer 1

Hint: They are also called acrania and are small, fish-like marine invertebrates. They are said to be the closest living relatives to the vertebrates. They have dorsal pharyngeal gill slits, nerve cord, and notochord.

Complete answer:
The hepatic portal system is in charge of directly carrying blood from the digestive system to the liver of the organ and is present in higher chordates. The cephalochordates notochord retains even in adulthood and has a hepatic portal system. Their fossil records extend back to about 525 million years ago. The adults reach a length of six to seven centimeters.
There are two families in this group which are Branchiostoma and Epigonichthys. The main difference is that Epigonichthys the gonads are restricted to one side of the body. The edible Branchiostoma is never sufficiently abundant for the source of food to humans or to be a part of the food chain. They rather have significance in evolution. Being the closest to vertebrates they provide hints for the history of the human lineage. In 1867 the connection was seen by Russian zoologist Aleksandr Kowalevsky in the embryological evidence and this proved in establishing that evolution has occurred. The sexes are separate and they reproduce sexually. Fertilization occurs in the water where eggs and sperm are spread in water. The stages at the beginning of their life cycle resemble those of both tunicates and vertebrates. The larvae spend most of the time in open water feeding and then undergo metamorphosis to become an adult.

<>So, the correct answer is ‘(c) Cephalochordates’.

Note: Hemichordates are marine deuterostome animals and are closely related to chordates. They have two main classes and they are Enteropneusta and Pterobranchia. They are divided into proboscis, collar, and trunk; and have open circulatory systems so do not have a hepatic portal system. The Urochordates are a phylum that has animals with dorsal nerve cords and notochords and has a circulatory system but does not have a hepatic portal system.