Question

The primitive multicellular animals having cellular level of organization are (a) Ctenophores (b) Sponges (c) Corals (d) Crustacean

Short answer

(b) Sponges

Step-by-step solution

Understanding the Terms

The first step in this biology exercise is to understand the meaning of 'cellular level of organization'. This means that the organisms are made up of cells that function independently of each other rather than working together as tissues and organs. This is, in essence, the first level of organization in the hierarchy of biological organization.

Identify the Organisms at the Cellular level

It's also important to know the different types of organisms mentioned in the exercise. Ctenophores are marine animals known for their radial symmetry and gelatinous bodies. Corals are marine invertebrates living in compact colonies. Crustaceans are a large group of arthropods, including crabs and lobsters. Finally, Sponges are simple multicellular organisms that lack true tissues and organs and show a cellular level of organization. These organisms filter feed and rely on the movement of water through their bodies to obtain food.

Match the Organism with the Level of Organization

After understanding the terms and the organisms, we can match the organisms with their level of organization. Out of the options given, only sponges match with the cellular level of organization. The rest of the organisms have a level of organization beyond the cellular.

Key concepts

Multicellular Animals

Multicellular animals are fascinating organisms that consist of multiple cells working together to sustain life. These animals have cells that collaborate to perform various tasks, unlike unicellular organisms that manage everything within one cell. As multicellular life forms evolved, they developed different strategies to organize and utilize their cells, leading to more complex body structures. Within the animal kingdom, the transition from single-celled organisms to multicellular ones marked a significant step in biological evolution. This transition paved the way for the diversity of life forms seen today, ranging from simple organisms like sponges to intricate creatures such as mammals and birds. Each multicellular group in the animal kingdom is adapted to its environment and has a unique level of organization that supports its survival.
Understanding multicellularity helps us appreciate the complexity and adaptability in the evolution of life.

Biological Organization

Biological organization refers to the hierarchy of complex biological structures and systems that define life using a reductionistic approach. Each level of organization is more complex and built upon the previous one. It begins at the smallest level with atoms and molecules and extends to cells, tissues, organs, and ultimately entire organisms and ecosystems.
In the context of the cellular level of organization, organisms like sponges exhibit the earliest form of this biological structuring. These organisms rely on individual cells to carry out tasks independently, rather than grouping cells into tissues or organs. This level of organization is crucial for primitive organisms, defining their simplicity and providing insights into early life on Earth.
As the organizational complexity increases, animals develop sophisticated body plans, enabling them to adapt efficiently to their environments. Biological organization helps us understand the complex interrelationships between biological entities at every level.

Sponges

Sponges, known scientifically as Porifera, represent some of the most primitive multicellular animals on Earth. They inhabit aquatic environments, primarily the ocean, and are characterized by their simple body structure. Unlike more evolved animals, sponges lack true tissues and organs but instead have bodies made up of various specialized cells.
The cellular level of organization in sponges means these cells independently perform tasks essential for survival, such as trapping food particles from the water. Sponges have tiny pores called ostia on their surfaces that allow water to enter, which is crucial for their filter-feeding mechanism. They play a vital role in their ecosystems by maintaining water quality and providing habitat for various marine organisms.
Despite their primitive nature, sponges exhibit unique abilities such as regeneration, where they can rebuild themselves from cell fragments. This evolutionary adaptation demonstrates their resilience and essential role in marine ecology.

Primitive Organisms

Primitive organisms refer to those early life forms that possess simple body structures and basic functional levels. These organisms typically lack complex systems for performing life processes. In a biological context, primitive organisms are closer to the common ancestor of all life forms.
Sponges are a classic example of primitive organisms, as they embody one of the earliest known branches of multicellular life. The simplicity of such organisms provides critical insights into the evolutionary processes that led to the vast array of life today. These organisms are significant for studying evolutionary biology as they help scientists understand how life transitioned from single-celled to more complex forms.
While primitive, these organisms possess features that have allowed them to survive for millions of years, adapting to changes within their environments. Their study is crucial in piecing together the history of life on Earth and showcases the foundational processes of biological evolution.