Sponges

Sponges of Kalymnos seabed

Sponges are a prominent invertebrate group. They are sessile animals. With limited ability for dispersal.

Sponges act as ecosystem engineers. Increasing habitat complexity. They develop complex associations with other  organisms. 

Sponges come at a plethora of shapes and colors.

Identified until now

1. Agelas oroides, Yellow sponge, Κίτρινο σφουγγάρι
2. Haliclona mediterranea, Pink Tube Sponge, Μωβ σωληνωτό σφουγγάρι
3. Haliclona rosea
4. Aplysilla sulfurea, Orange Encrusting Sponge, Πορτοκαλί εξωσκελετικό σφουγγάρι
5. Dysidea avara  - Pink Sponge - Ροζ Σφουγγάρι 
6. Axinella cannabina - Orange axinella - Σταθόρι   
7. Axinella spp. – Yellow axinella - Κίτρινο αξινέλι (κίτρινοι σπόγγοι με διακλαδώσεις)
8. Aplysina aerophoba, Yellow Tube Sponge, Κίτρινο Σωληνωτό Σφουγγάρι
9. Raspaciona aculeata, Red hispid sponge, Κόκκινο Τριχωτό Σφουγγάρι
10. Petrosia ficiformis, Stony Sponge, Πετρώδες σφουγγάρι, photo2
11. Sarcotragus spinulosus, Black Sponge, Μαύρο Σφουγγάρι
12. Crambe crambe - Orange-red Encrusting Sponge - Πορτοκαλί-Κόκκινο Εξωσκελετικό Σφουγγάρι 
13. Clathrina coriacea
14. Spongia agaricina - Elephant Ear - Λαγόφυτο
15. Chondrosia reniformis - Kidney shaped Sponge - Σφουγγάρι σε σχήμα νεφρού - (Σβούρδουκλας)
16. Phorbas tenacior - Blue Encrusting Sponge - Μπλέ Εξωσκελετικό Σφουγγάρι - Identified by Maria Sini
17. Dysidea fragilis - Identified by Maria Sini

From EOL (Encyclopedia of life)

Sponges (phylum Porifera) are an exclusively aquatic and, with a few exceptions, a filter-feeding group of animals. The group consists of approximately 15,000 extant species in three distinct groups:

• the glass sponges (Class Hexactinellida) -  mainly restricted to deeper waters (200 to > 6000 m)
• the calcareous sponges (Class Calcarea) - Fossil species
• the horny (=fibrous) sponges (Class Demospongiae) - Fossil species

From Marine Drugs: Sponges for new medicines

Marine sponges belonging to the phylum Porifera (Metazoa), evolutionarily the oldest animals are the single best source of marine natural products. 

Discovery of marine derived natural products is a promising, but comparatively new field. It has been estimated that by 2010 more than 15,000 new marine natural products (NMNP) had been discovered. Among all the marine organisms investigated, marine sponges (Porifera) are recognized as the richest sources of NMNP, with about 4851 compounds to date, contributing to nearly 30% of all marine natural products discovered so far. 

With this myriad of NMNP available, numerous studies have revealed a broad spectrum of biological activities for these compounds, including anticancer, antiviral, antibacterial, antifungal, antiprotozoal, anthelmintic, anti-inflammatory, immunosuppressive, neurosuppressive, neuroprotective, antifouling and a range of other bioactivities. Read the full article

From Wikipedia

Sponges are animals of the phylum Porifera ( meaning "pore bearer"). They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process.

Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes. http://en.wikipedia.org/wiki/Sponge

• Sessile. 
• Anatomy difficult to describe.
• Soft texture to the touch.

http://www.european-marine-life.org/02/sponges-gallery.php