1. Sponges are a diverse group of sometimes common types, with about 5000 species known across the world.
Sponges are primarily marine, but around 150 species live in fresh water.
Sponges have cellular-level organization, meaning that that their cells are specialized so that different cells perform different functions, but similar cells are not organized into tissues and bodies are a sort of loose aggregation of different kinds of cells.
This is the simplest kind of cellular organization found among parazoans.

2. sponges include a system of pores (also called ostia) and canals, through which water passes.
Water movement is driven by the beating of flagellae, which are located on specialized cells called choanocytes (collar cells).
Sponges are either radially symmetrical or asymmetrical.
They are supported by a skeleton made up of the protein collagen and spicules
Reproduction by sponges is by both sexual and asexual means.

3. Asconoid Example:: Leucosolenia
Sponges have three different types of body plans
Asconoid
sponges are shaped like a simple tube perforated by pores.
The open internal part of the tube is called the spongocoel; it contains the collar cells.
There is a single opening to the outside, the osculum.
Example:: Leucosolenia
Classification
Phylum : Porifera
Class : Calcarea
Order : Homocoela
Genus : Leucosolenia

5. Syconoid Phylum: Porifera Class : Calcarea Order : Heterocoe
sponges tend to be larger than asconoids and have a tubular body with a single osculum.
The synconoid body wall is thicker and the pores that penetrate it are longer, forming a system of simple canals.
These canals are lined by collar cells, the flagellae of which move water from the outside, into the spongocoel and out the osculum.
Example:: Sycon
Classification
Phylum: Porifera
Class : Calcarea
Order : Heterocoe
Genus : Sycon

7. Leuconoid
These are the largest and most complex sponges.
These sponges are made up of masses of tissue penetrated by numerous canals.
Canals lead to numerous small chambers lined with flagellated cells.
Water moves through the canals, into these chambers, and out via a central canal and osculum.

8. Example:: Euspongia
Classification
Phylum :Porifera
Class : Demosongia
Order : Keratosa
Genus : Euspongia
Euspongia is the common bath sponge.
It is a deep sea form and is found in the Mediterranean Sea.
It is like a cup and the skeleton is made of sponging fibres only (siliceous spiculels are absent).
It is used during bath to clean body

10. Hydra look very much like miniature sea anemones.
Classification:
Phylum: Coelentrata
Class : Hydrozoa
Order : Diploblastica
Genus : Hydra
Hydra look very much like miniature sea anemones.
They can be white brown or green.
Hydra have a saclike body and a circle of tentacles at around the body opening.

11. This opening is used for both taking in food and eliminating wastes.
Hydra don't have eyes but they can sense light
They will also reproduce easily, either asexually, by forming buds or by laying a single egg.
Hydra are carnivorus and will eat anything they can manage to catch including single celled animals, small crustaceans, worms, insects, and other tiny animals

14. Fasciola

15. Fasciola life cycle

16. Fasciola eggs

17. Fasciola intermediate host
Lymnaea sp.

18. Cercaria of Fasciola

19. The infective stage of Fasciola
Encysted metacercaria

20. Fasciola