Difference Between Sponge and Hydra

The key difference between sponge and hydra is that sponges are primitive multicellular animals belonging to phylum Porifera that show cellular level organization while hydra is a multicellular animal belonging to phylum Coelenterate that shows tissue-level organization.

Kingdom Animalia is the largest kingdom comprising of multicellular eukaryotic animals. Animals can be classified into major phyla as Porifera, Coelenterata, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata and Chordata. Sponges are members of phylum Porifera. They are simple multicellular animals that show cellular level organization. They do not have tissues. Hydra is a member of phylum Coelenterata that shows tissue-level organization.

1. Overview and Key Difference
2. What is Sponge
3. What is Hydra
4. Similarities Between Sponge and Hydra
5. Side by Side Comparison – Sponge vs Hydra in Tabular Form
6. Summary

What is Sponge?

Sponges are primitive multicellular animals of kingdom Porifera. They are invertebrates that have a cellular level organization. They show minimal differentiation and don’t have true tissues. Moreover, they don’t have internal organs. Sponges are non-motile and often found attached to a solid surface. They are marine organisms. Moreover, they are asymmetrical organisms. There are four different classes of sponges as Calcarea, Demospongiae, Scleropongiae and Hexactinellida.

Figure 01: Sponges

These organisms have a central canal and water enters from one side and leaves from the other side. They obtain nutrients and oxygen through the water flow. Therefore, they are filter feeders. They eat tiny, floating organic particles and plankton from the water flow. Furthermore, waste removal also takes place through the water flow in sponges.

Sponges have different colours and shapes. They may reproduce sexually (by the formation of gametes) and asexually (by fragmentation). Most importantly, most sponges are hermaphrodites, having both male and female reproductive parts.

What is Hydra?

Hydra is a genus of multicellular freshwater animals belonging to phylum Coelenterata. They belong to class hydrozoa. Hydra is also called polyp due to its special power of regeneration. Hydra is a sessile animal often found attached to a solid surface or to submerged vegetation. The body of hydra is cylindrical/tubular in shape and radially symmetrical.

Figure 02: Hydra

Hydra is carnivorous. It eats small insects, insect larvae and small crustaceans. Moreover, hydra reproduces sexually as well as asexually. Budding is the asexual form of reproduction while the development of temporary structures called gonads takes place during sexual reproduction. Most hydra species are dioecious while some species are monoecious or hermaphrodite.

What are the Similarities Between Sponge and Hydra?

Sponge and hydra belong to Kingdom Animalia.
They are invertebrates.
Moreover, they are aquatic, multicellular organisms.
They reproduce sexually as well as asexually.
Both sponges and hydra are sessile and remain attached to a solid object.

What is the Difference Between Sponge and Hydra?

Sponge is a primitive multicellular animal that belongs to phylum Porifera while hydra is the multicellular freshwater animal that belongs to phylum cnidaria. So, this is the key difference between sponge and hydra. Besides, sponge shows cellular-level organization while hydra shows tissue-level organization.

Moreover, sponges are mostly asymmetrical, while hydra is radially symmetrical. Also, most sponges are marine animals, while few species are freshwater organisms. On the other hand, hydra is a freshwater organism. Furthermore, another difference between sponge and hydra is the nutrition. Sponges eat tiny, floating organic particles and plankton from the water the flows. In contrast, hydra is carnivorous. It feeds on small insects, insect larvae and small crustaceans.

You can find more details from the below infographic of difference between sponge and hydra.

Summary – Sponge vs Hydra

Sponge and hydra are two types of aquatic animals which are multicellular eukaryotes. Sponges are primitive animals which have cellular-level organization. In contrast, hydra is an animal that has a tissue-level organization. Moreover, sponge belongs to phylum Porifera while hydra belongs to phylum cnidaria. Furthermore, sponges are asymmetrical while hydra is radially symmetrical. Thus, this summarizes the difference between sponge and hydra.

Reference

1. “Hydra: History, Habitat and Locomotion (With Diagram).” Biology Discussion, 2 May 2016, Available here.

2. “Classification of Animal Kingdom (Animalia).” PMF IAS, 12 July 2016, Available here.

Image Courtesy:

1. “A Guantanamo sponge -a” By Timothy W. Brown – (Public Domain) via Commons Wikimedia
2. “Hydra-Foto” By Flatters & Co. (photograph) – Original source: Marvels of the universe. A popular work on the marvels of the heavens, the earth, plant life, animal life, the mighty deep, with an introd. by Lord Avebury and with contributions by leading specialists, etc., published in 2 vols in London 1911-1912. Page 264 [1]. (Public Domain) via Commons Wikimedia