Question

Exogenous budding is seen in case of (a) Scypha (b) Euspongia (c) Spongilla (d) Hyalonema

Short answer

The correct answer is (c) Spongilla.

Step-by-step solution

Understanding the question

The question requires knowledge of different types of sponges, specifically their reproduction modes - namely, exogenous budding. Exogenous budding is an asexual method for reproduction in which the bud forms an outward growth from the parent organism, which eventually detaches and becomes independent.

Identifying the correct answer

Investigate each of the options given. Scypha, Euspongia and Hyalonema are marine sponges, while Spongilla is a freshwater sponge. Exogenous budding is a reproductive method found in freshwater sponges. Therefore, the correct choice is Spongilla.

Key concepts

Asexual Reproduction

Asexual reproduction is a biological process where an organism produces offspring without the involvement of genetic exchange from two parents. This form of reproduction is efficient and typically requires less energy than sexual reproduction, as it does not require mating. A prime example of asexual reproduction in the animal kingdom is exogenous budding, a method where a new organism (a bud) grows from the body of the parent. When the bud matures, it detaches and becomes an independent organism, genetically identical to the parent. This type of reproduction is especially common in simpler organisms, such as bacteria, plants, and certain animals like sponges. The advantages include rapid population increase and the ability to colonize environments quickly. However, because the offspring are clones, there is less genetic diversity, which can be a drawback in changing environmental conditions.

Freshwater Sponge Reproduction

Freshwater sponges, like their marine counterparts, can reproduce in various ways, including sexually and asexually. For many freshwater sponges, asexual reproduction is a key method of propagation, especially in environments that are less stable or in seasons when sexual reproduction is not favorable. Exogenous budding is a common asexual strategy seen in these species. Unlike marine sponges, which often rely on the water currents to disperse their larvae, freshwater sponges' buds sometimes remain attached to the parent sponge throughout the winter, providing an efficient survival strategy in temperate zones where water bodies can freeze over. The buds, known as gemmules, can withstand harsh conditions, ensuring the survival of the species until conditions improve, at which point they can attach to a substrate and grow into new, genetically identical individuals.

Spongilla

Spongilla is a genus that belongs to the family Spongillidae, consisting of freshwater sponges. These sponges are adapted to life in still or slow-moving freshwater bodies like lakes, rivers, and canals. With their porous bodies, they filter feed on microscopic plants, bacteria, and organic debris. A signature reproductive feature of Spongilla is exogenous budding, which allows them to thrive in their freshwater habitats. During this process, they produce gemmules, which are resilient asexual reproductive structures designed to survive freezing temperatures and droughts. As they emerge in the spring or when conditions become favorable, these gemmules germinate, giving rise to new sponges that contribute to the colonization and persistence of Spongilla populations. The resilience and adaptability of Spongilla illustrate the effectiveness of asexual reproduction strategies like exogenous budding in varying environmental conditions.