ZOO511 Practical Lab Manual Updated

Practical # 1

The poriferans are commonly known as sponges. They play a crucial role in aquatic ecosystem.

•  Simplest and primitive organisms
•  First multicellular animals
•  Porous body structure
•  Cellular level of body organization
•  Sessile and benthic organisms

1. Body Structure:

Porifera are the simplest type of multicellular animals. They are sessile and lack true tissues and organs.

2. Porous structure:

They consist of a porous body covered in tiny openings called ostia, through which water is drawn.

3. Water Canal System:

Water flows through the sponge's body, facilitated by specialized cells called choanocytes which flow out through large opening called osculum.

4. Skeleton:

Skeleton consists of spongin fibres and siliceous or calcareous spicules.

5. Nutrition:

They show holozoic nutrition which involves absorbing or ingesting solid organic food particles from water.

6. Reproduction:

They reproduce either sexually by releasing male and female gametes into the water and asexually by budding. They have also capability of regeneration

7. Classification:

This phylum contains three main classes;

a. Class Demospongiae b. Class Calcarea c. Class Hexactinellida

Examples: Spongia, Sycon and Grantia.

Spongia officinalis

Class: Demospongiae Order: Dictyoceratida Family: Spongiidae

1. Spongia is commonly called as “Bath Sponge”.
2. It is light grey to black in color.
3. It grows in massive, globular lobes with fine openings which are slightly elevated and have cone-shaped voids (conules).
4. Oscula can either be scattered or at the tip of the lobes.
5. It has a network of canals and chambers.
6. It consists of ectosomal skeleton and choanosomal skeleton.
7. The choanocytes lining the canals create water currents that bring in food particles, which are then captured and digested.
8. Body is composed of spongin fibres and inclusions such as sand grains and spicules.

Spongia officinalis is typically found in shallow marine environments, attached to rocks or other substrates. It thrives in regions with moderate water currents, allowing it to efficiently filter water for nutrients.

Figure shows the specimen of Spongia officinalis