Halichondria panicea, commonly known as the breadcrumb sponge, is a species of marine demosponge

Demosponge

The Demospongiae are the largest class in the phylum Porifera. Their "skeletons" are made of spicules consisting of fibers of the protein spongin, the mineral silica, or both. Where spicules of silica are present, they have a different shape from those in the otherwise similar glass sponges...

 belonging to the family Halichondriidae

Halichondriidae

Halichondriidae is a family of marine demosponges belonging to the order Halichondrida. These sponges have a skeleton consisting of dense bundles of spicules occurring in a more or less random pattern.-References:**...

. This is an abundant sponge of coastal areas of the North Atlantic and the Mediterranean Sea

Mediterranean Sea

The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...

 ranging from the intertidal zone to a recorded depth of over 550 m. It is very tolerant of a wide range of coastal habitats, including strong currents, high salinity

Salinity

Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

 and exposure to powerful wave action. Its only requirement is a rocky substrate

Substrate (biology)

In biology a substrate is the surface a plant or animal lives upon and grows on. A substrate can include biotic or abiotic materials and animals. For example, encrusting algae that lives on a rock can be substrate for another animal that lives on top of the algae. See also substrate .-External...

 which can include small cobbles

Cobble (geology)

A cobble is a clast of rock with a particle size of to based on the Krumbein phi scale of sedimentology. Cobbles are generally considered to be larger than pebbles and smaller than boulders . A rock made predominantly of cobbles is termed a conglomerate....

.

Morphology

Halichondria panicea occurs in a very wide range of forms and can be difficult to identify. Some forms have a granular surface which gives rise to the common name but sometimes the surface is smooth, even glassy. The surface is often marked with pores (osculae) which can extend into tubular "chimneys" in wave-sheltered habitats. The overall form is determined largely by the habitat: wave-exposed forms usually form thin widespread sheets but wave-sheltered forms often form massive encrustations up to 20 cm thick. This diversity has led to its being described as a new species 56 times.

The colour is also variable. The "natural" colour is cream or grey: this is usually found in specimens from relatively deep water. However at shallower depths, the sponge is usually green due to symbiotic algae

Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 which live close to the surface of the sponge. At intermediate depths the sponge tends to be green in summer, cream or grey in winter. It smells like "exploded gunpowder".

Biology

Halichondria panicea is a suspension feeder feeding mainly on phytoplankton

Phytoplankton

Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...

. For such a common species, relatively little is known about its reproduction: It appears to be a hermaphrodite

Hermaphrodite

In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...

 and oogenesis

Oogenesis

Oogenesis, ovogenesis or oögenesis is the creation of an ovum . It is the female form of gametogenesis. The male equivalent is spermatogenesis...

has been reported as occurring in a very narrow timeband within a single population although exceptions have been observed.

Other names

1. Halichondria panicea Pallas, 1766
2. Halina panicea Pallas, 1766
3. Spongia panicea Pallas, 1766
4. Spongia tomentosa Linnaeus, 1767
5. Spongia cristata Ellis & Solander, 1786
6. Spongia tubulosa Ellis & Solander, 1786
7. Spongia urens Ellis & Solander, 1786
8. Halichondria papillaris Linnaeus, 1791
9. Alcyonium manusdiaboli sensu Esper, 1794
10. Spongia compacta Sowerby, 1806
11. Alcyonium medullare Lamarck, 1815
12. Halichondria albescens Rafinesque, 1818
13. Seriatula seriata Grant, 1826
14. Spongia seriata Grant, 1826
15. Halichondria sevosa Johnston, 1842
16. Halichondria reticulata Lieberkühn, 1859
17. Halichondria coccinea Bowerbank, 1861
18. Hymeniacidon coccinea Bowerbank, 1861
19. Halichondria brettii Bowerbank, 1866
20. Hymeniacidon brettii Bowerbank, 1866
21. Hymeniacidon fallaciosus Bowerbank, 1866
22. Halichondria caduca Bowerbank, 1866
23. Halichondria glabra Bowerbank, 1866
24. Halichondria incerta Bowerbank, 1866
25. Halichondria lactea Bowerbank, 1866
26. Halichondria membrana Bowerbank, 1866
27. Hymeniacidon fragilis Bowerbank, 1866
28. Hymeniacidon lactea Bowerbank, 1866
29. Hymeniacidon membrana Bowerbank, 1866
30. Hymeniacidon thomasii Bowerbank, 1866
31. Hymeniacidon parfitti Parfitt, 1868
32. Hymeniacidon reticulatus Bowerbank, 1866
33. Pellina bibula Schmidt, 1870
34. Spuma borealis var. convoluta Miklucho-Maclay, 1870
35. Spuma borealis var. tuberosa Miklucho-Maclay, 1870
36. Spuma borealis var. velamentosa Miklucho-Maclay, 1870
37. Halichondria ambigua Bowerbank, 1874
38. Halichondria edusa Bowerbank, 1874
39. Halichondria firmus Bowerbank, 1874
40. Halichondria pannosus Verrill, 1874
41. Hymeniacidon firmus Bowerbank, 1874
42. Hymeniacidon solida Bowerbank, 1874
43. Hymeniacidon tegeticula Bowerbank, 1874
44. Amorphina appendiculata Schmidt, 1875
45. Halichondria paciscens Schmidt, 1875
46. Amorphina paciscens Schmidt, 1875
47. Halichondria coralloides Bowerbank, 1882
48. Isodictya crassa Bowerbank, 1882
49. Isodictya perplexa Bowerbank, 1882
50. Microciona tumulosa Bowerbank, 1882
51. Amorphina grisea Fristedt, 1887
52. Halichondria grisea Fristedt, 1887
53. Menanetia minchini Topsent, 1896
54. Halichondriella corticata Burton, 1931
55. Trachyopsilla glaberrima Burton, 1931
56. Halichondria topsenti de Laubenfels, 1936