Problem 168 - Objective Biology for NEET

Question

The class name 'cyclostomata' means (a) Marine, but reproduction takes place in fresh water (b) Mouth is anterio ventral, suctorial and circular (c) Ectoparasite of fishes (d) Jaws are absent

Step-by-Step Solution

Answer

The correct answer is (d) Jaws are absent.

Step 1: Understanding The Question

First, the meaning of 'cyclostomata' needs to be determined.

Step 2: Research The Meaning

Upon researching, 'cyclostomata' is a class of Agnatha that are characterized by the absence of jaws.

Step 3: Choosing The Correct Answer

The answer should be the one that talks about the absence of jaws.

Key Concepts

Agnatha

Agnatha is a superclass in the subphylum Vertebrata. It includes jawless fish, which are among the most primitive vertebrates. These creatures are intriguing because they give us insights into early vertebrate evolution. Agnathans have varied body forms, often cylindrical and elongated, with smooth and scale-less skin. This lack of complex structures, like jaws, makes them fascinating study subjects in marine biology.

• The absence of jaws sets Agnatha apart from other vertebrates.
• They have a cartilaginous skeleton, rather than a bony one.
• Living agnathans include lampreys and hagfish.

Their simplicity and ancient lineage help scientists understand the evolutionary processes that led to more complex vertebrates.

Jawless fish

Jawless fish are a primitive group of fish within the class Cyclostomata. As the name suggests, jawless fish lack a structured jaw, which profoundly affects their feeding methods.
Instead of biting and chewing, they rely on other mechanisms to feed, often sucking or scraping food.

• These fish have circular mouths, perfectly adapted to their feeding style.
• Their digestive systems are relatively simple compared to modern fish with jaws.
• Notable examples are the hagfish and lampreys, which have adapted unique feeding habits to compensate for their lack of jaws.

This atypical feeding mechanism often ties into their roles in the ecosystem, specifically as scavengers or parasites.

Ectoparasite of fishes

Some species within the Cyclostomata class, especially lampreys, act as ectoparasites. This means they live on the outside of their host and derive nutrients by feeding on the host's bodily fluids.
This type of relationship can significantly impact fish populations in their ecosystems.

• They attach to other fish using their suction-like mouths.
• During feeding, they often bore into the host’s skin to access blood or other body fluids.
• The impact on the host can vary but may include reduced growth rates or even death.

Understanding these relationships helps scientists study marine population dynamics and the ecological impact of parasites.

Marine biology

Marine biology is the scientific study of marine life, habitats, and ecosystems. Within this field, understanding jawless fish like those in the Cyclostomata class helps elucidate the complexities of evolutionary pathways and ecological niches in marine environments.

• Marine biologists study not just the organisms but their interactions with each other and the environment.
• They aim to understand processes from molecular biology to ecosystem functioning.
• Research can shed light on conservation needs and the impact of human activities on marine ecosystems.

Focusing on jawless fish, marine biology strives to uncover the roles these ancient creatures play within their habitats, offering insights into both ancient evolutionary processes and current ecological dynamics.