Sponges (Phylum Porifera)
Barrel-shaped Stelletta māori with an encrustation of bright orange Desmacella dendyi, with Tethya fastigata to the lower right. A small branching axinellid sponge is seen on the upper right. Photographer Franz Smith.
Michelle Kelly and Franz Smith
General Description
Sponges are among the oldest living multicellular organisms, with a fossil record dating back to about 600 million years. They are often considered to be the most primitive of animal groups, largely due to their apparently simple body structure that lacks actual tissues or organs, yet they represent a highly specialised and successful group of benthic suspension-feeders in marine and fresh waters. Indeed, so adaptable are sponges that a small group in the deepest ocean have successfully switched to a carnivorous lifestyle. Their persistence throughout geological time, wide global distribution, and occurrence in diverse habitat types are evidence of their adaptability.
The sponge phylum, Porifera "the pore bearers", is divided into three distinct classes. The Calcarea have spicules of calcium carbonate in the calcite form and are commonly known as "calcareous" sponges. The Demospongiae, which is the most diverse class of sponges, have skeletons of two components, a mineral skeleton of silica spicules, and an organic skeleton made of diverse forms of spongin (collagen) fibre. Some sponges lack spicules, some lack fibre, and some combine the two. Some incorporate sand into their skeleton to various degrees. Some demosponges (the "sclerosponges") form a stony base of calcium carbonate in the aragonite form, with a veneer of living "tissue" on the surface. These sponges also produce silica spicules. The Hexactinellida, commonly known as the glass sponges, have siliceous spicules with a hexactine (six-ray) design.
The adult form of the sponge is sessile, most commonly attached to hard substrate such as rock, or they may be basally or wholly buried in sediment. They are suspension-feeders, deriving most of their energy from bacteria and suspended particles in the water column. Sponges have impressive filtering capabilities; some sponges are able to filter many times their own volume of water per day.
The growth form of sponges varies immensely, from thin encrusting to massive hemispherical forms, from branching and tree-like forms, to plate or vase shapes, to spherical-, barrel- or volcano-shaped forms. The sponge texture is highly diverse, varying from dense, stony, coral-like cups to smooth, slippery, skin-like structures, and reflects the underlying architecture of the spicules and fibres and the relative proportions and arrangements of these components of the skeleton. These characters (spicules and fibres) are fundamental to the way that we classify sponges, with skeletal arrangements characterising groups of sponges that are related to each other. Sponge colour ranges across the spectrum from blue, violet, lilac, fuschia, magenta, and red, to white, cream, lemon, green, orange, brown, and black. Some of the variation in colours can be attributed to microorganisms living within the sponge, but mostly to carotenoid pigments.
The mode and timing of reproduction in sponges varies across taxonomic levels, but is primarily in two forms. Fertilisation of gametes is internal in brooding sponges with the development of embryos within the sponge, while in other species the eggs and sperm are released into the water column. In the latter, eggs are fertilised externally, forming larvae that disperse by swimming or crawling along the substrate, usually away from light. Asexual reproduction is also a common method of propagation in sponges, with budding, or fragmentation in large branching sponges, or resting stages, also known as gemmules, in colder climates and in freshwater sponges.
Some sponges provide habitats for a variety of other marine organisms inside the aquiferous canals (crustaceans, polychaetes, juvenile fish), within their surface matrix (barnacles, bivalve molluscs), encrusting (other sponges, ascidians, bryozoans) or perching on (nudibranchs, crinoids and amphipods) their surface. In suitable habitats sponges may form "gardens" en masse, increasing habitat structure and thus, the general diversity of the area.
Sponges contribute significantly to the dynamics of reef environments; they provide an important food source for a number of different organisms including nudibranchs and sea stars, fishes and turtles, and some are capable of boring destructively into calcareous rock. Their strong chemical and physical competitive overgrowth interactions enable sponges to successfully compete for space and food. The production of novel, potent, biologically active chemical compounds in sponges is thought to play a role in competition, and in the deterrence of predators, but may also be the byproduct of microorganism symbionts. Whatever the origin and function, the study of the types and function of these compounds forms the basis of the rapidly growing and exciting fields of biomedicine and chemical ecology.
Due to a lack of comprehensive locality-specific collections and difficulties in taxonomic determination, the total number of sponge species in the world is uncertain. At present there are about 8000 described species, but a conservative estimate would indicate that this number is likely to double or triple as taxonomic information improves. In the New Zealand region, there are presently just over 700 described species, however it is estimated that with more comprehensive sampling, this number is likely to be well over 1500. One of the most remarkable characteristics of the New Zealand sponge fauna is the level of endemicity, where over 95% of the species appear to be are endemic to the region. There are five endemic genera (Manawa, Sigmarotula, Lepidothenea, Lamellomorpha, and Acanthoclada), and several are known from recent collections. Of the 72 recognised demosponge families, 55 (ie, 76%) are found in the New Zealand region. Of the 11 "lithistid" sponge families presently recognised, 8 are found in New Zealand.
Status
New Zealand sponges are most abundant in habitats undisturbed by commercial benthic fishing activity and terrigenous sedimentation input through coastal development. Generally sponges are not endangered. However, special spots of high diversity such as Spirits Bay, in hydrothermal areas, and on seamounts, are under pressure from benthic trawling in particular. The need and potential for conservation of sponge habitats is considerable.
Key Locations
At the regional level, sponges are abundant in areas of hydrothermal activity such as in the Bay of Plenty and the Kermadec Ridge, and in areas of current convergence and high current activity, such as in Spirits Bay, around North Cape and the Three Kings Islands. Offshore continental shelf carbonate banks are also particularly good habitat for sponges, with other invertebrates such as hydroids and bryozoans. Sponges are amongst the dominant macroinvertebrates on deepwater seamounts.
Threats
Commercial benthic trawl fishing activity; terrigenous sedimentation input through coastal development.
Typical Habitats
Most sponges live openly on rocky reef, or attached to shell and basement substrate beneath sand; many are cryptic, living under overhangs and in caves. Many are rooted in soft mud and sediments.
State of Information
The taxonomy of New Zealand sponges is reasonably well known, but complete distribution data is lacking. Reproductive biology and timing, and food sources are perhaps the least known of sponge biology and ecology.
Significance for Maori
Although many species of sponge are used by Pacific islanders for various tasks such as fishing, caulking, scrubbing implements, and as sources of biomedicine, the use of sponges by Maori is unrecorded. A report of large volumes of spicules in a northland Maori midden indicates that they may have been used in the past.
Key References
Bergquist, P R. 1978. Sponges. University of California Press, Los Angeles. 268pp.
Hooper, J N A, Van Soest, R W M and F Debrenne. 2002: Phylum Porifera Grant, 1836. In: Hooper, J N A and van Soest, R W M (eds). Systema Porifera: A Guide to the Classification of Sponges. Kluwer Academic/Plenum Publishers, New York: 9-13.
Kelly, M, Edwards, A R, Wilkinson, M R, Alvarez, B, Cook, S. de C, Bergquist, P R, Buckeridge, J S, Campbell, H, Reiswig, H M and C Valentine. 2006: Phylum Porifera Sponges. In Gordon, D.P. (ed). In press: The New Zealand Inventory of Biodiversity Volume 1. Kingdom Animalia: Radiata, Lophotrochozoa, and Deuterostomia. Canterbury University Press, Christchurch.
Table 19: Sponges (Phylum Porifera) in New Zealand.
The number of endemic species within each order are not known precisely, but are thought to be about 95 per cent of the total, except for the one Halisarcida species which is thought to be introduced.
| Class | Order | Endemic Species | Total Species |
|---|---|---|---|
| DEMOSPONGIAE | ASTROPHORIDA | 61 | |
| CHONDROSIDA | 1 | ||
| DENDROCERATIDA | 7 | ||
| DICTYOCERATIDA | 56 | ||
| HADROMERIDA | 79 | ||
| HALICHONDRIDA | 68 | ||
| HALISARCIDA | 1 | ||
| HAPLOSCLERIDA | 93 | ||
| HOMOSCLEROPHORIDA | 3 | ||
| LITHISTIDA | 29 | ||
| POECILOSCLERIDA | 197 | ||
| SPIROPHORIDA | 9 | ||
| VERONGIDA | 1 | ||
| ~575 | 605 | ||
| HEXACTINELLIDA | AMPHIDISCOSIDA | 29 | |
| HEXACTINOSIDA | 12 | ||
| AULOCALYCOIDA | 1 | ||
| LYSSACINOSIDA | 33 | ||
| ~71 | 75 | ||
| CALCAREA | CLATHRINIDA | 13 | |
| LEUCOSOLENIDA | 36 | ||
| BAERIIDA | 4 | ||
| ~50 | 53 | ||
| Grand Total | 696 | 733 |
(After Kelly et al., 2006 in press)
Figure 49: Ear sponge Aciculites pulchra annual distribution.
Figure 50: Onion sponge Monosyringiea mortenseni annual distribution.