Question

Choanocytes are a. a group of protists that are believed to have given rise to animals. b. specialized cells of sponges that function to trap and eat small particles. c. cells that make up the gelatinous layer in sponges. d. cells of sponges that function to transfer nutrients to other cells. e. cells that form spicules in sponges.

Short answer

The correct answer is option b. Choanocytes are specialized cells of sponges that function to trap and eat small particles.

Step-by-step solution

Identify the subject of the question

The question is about Choanocytes. Choanocytes are a type of cell found in sponges.

Evaluate Each Option

Each option provides a different definition of Choanocytes. Analyzing each option carefully to match it with the correct definition will yield the correct answer.

Match the correct option

Upon analysis, it is found that Choanocytes are specialized cells of sponges that function to trap and eat small particles.

Key concepts

Sponge Anatomy

Sponges, belonging to the phylum Porifera, are simple multicellular organisms characterized by their porous structure. Their biology is fascinating due to the simplicity and efficiency of their form. Sponges lack true tissues and organs but have a unique structural framework.

Key components of sponge anatomy include layers of specialized cells forming their body walls. Among these cells are the pinacocytes forming the outer layer, porocytes creating tiny openings called ostia, and mesohyl acting as a gelatinous matrix inside. At the heart of sponge anatomy are the choanocytes, which line the inner chambers and are pivotal to a sponge's feeding mechanism.

Sponges draw water through their porous bodies, passing it over choanocytes to filter and capture food particles. This process is crucial for nutrient intake and overall survival, highlighting how their anatomy supports a continuous, efficient flow system.

Cell Specialization

Cell specialization refers to the unique and distinct functions that cells perform in an multicellular organism. In sponges, cell specialization is evident through the different types of cells adapted to carry out varied roles.

Choanocytes, also referred to as collar cells, are a prime example of cell specialization within sponges. These cells have a flagellum surrounded by a collar of microvilli and are specialized for filtering. The coordinated beating of the flagella creates currents that draw water through the sponge, allowing them to trap particles and plankton for consumption.

Other specialized cells in sponges include amoebocytes, which move through the mesohyl and transport nutrients, and spicule-forming cells, which contribute to structural support. Each type of cell in a sponge is uniquely adapted to perform specific functions, working collectively to maintain the sponge's life.

Animal Evolution

The evolution of animals from simple to complex forms gives us insight into the development of complex life. Sponges, as some of the earliest forms of multicellular life, provide a window into early animal evolution.

The simplicity of sponges, with their specialized cells and lack of complex tissues, suggests a significant evolutionary stepping stone from unicellular to multicellular organisms. It’s believed that sponges share a common ancestor with other animals, providing clues to the characteristics that might have been present in early multicellular life forms. Despite their simple design, sponges reflect a major adaptation: the transition from life as single-celled to complex multi-celled organisms.

This evolutionary perspective emphasizes the importance of sponges in the animal kingdom, representing a bridge between protists and more advanced animals, shedding light on the evolutionary process that led to increased structural complexity.

Protists and Animals

Protists and animals are two categories of organisms that show fascinating evolutionary links. Protists, often single-celled organisms, are incredibly diverse and are considered a catch-all category for many eukaryotic life forms.

Choanoflagellates, a group of protists, are of special interest due to their striking resemblance to the choanocytes of sponges. They bear a whip-like flagellum surrounded by a collar structure. This similarity suggests that choanoflagellates could be an ancestor or a close relative of early animals, including sponges.

The transition from protist-like organisms to animals marks a fundamental leap in biological complexity. This shift involves the aggregation of individual protists into colonies, eventually giving rise to the specialized cells found in sponges. Understanding the relationship between protists and animals helps scientists trace the origins and evolution of animals, illustrating the gradual sophistication of life from unicellular to complex multicellular organisms.