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Although they may look plant-like, sea sponges are the simplest of multi-cellular animals. A sea sponge is a bottom-dwelling creature, which attaches itself to something solid in a place where it can, hopefully, receive enough food to grow. The scientific term for sea sponges is Porifera, which literally means "pore-bearing." A sea sponge is covered with tiny pores, called ostia, which lead internally to a system of canals and eventually out to one or more larger holes, called oscula. Within the canals of the sea sponge, chambers are lined with specialized cells called choanocytes, or collar cells. The collar cells have a sticky, funnel shaped collar and a hair like whip, called a flagellum. The collar cells serve two purposes. First, they beat their flagella back and forth to force water through the sea sponge. The water brings in nutrients and oxygen, while it carries out waste and carbon dioxide. Second, the sticky collars of the collar cells pick up tiny bits of food brought in with the water. Another type of cell, called an amebocyte, takes the food to other cells within the sea sponge. Sea Sponges are very effective filter feeders, since they are able to capture and eat particles as small as bacteria as well as much larger particles.
The "skeleton" of the sea sponge is composed of tiny needle-like splinters called spicules, a mesh of protein called spongin, or a combination of both. Many sea sponges can only be identified by microscopic examination of the skeleton, which makes certain identification from photographs difficult.
Sea Sponges - Reproduction
Most sea sponges are hermaphroditic (having both sexes in one), but produce only one type of gamete per spawn. (i.e. some play the male role and the other plays the female role, even though they are both capable of playing either role). The sperm is released into the water column by the "male" sponge and finds its way to the "female" sponges, where fertilization occurs internally. Eventually, the planktonic larvae are released from the female sponge and float around in the water column as Zooplankton for only a few days. They then settle down and start growing. The next time the sponges reproduce, they may change sexual roles.
There are many different types of sea sponges in the world's oceans, and, contrary to popular belief, they can be quite colorful and beautiful. Sea Sponges come in two basic types: encrusting or freestanding. Although neither of these names are part of the true classification of sea sponges, it does make it a bit easier to organize them.
Encrusting sea sponges typically cover the surface of a rock in the same manner that moss covers a rock on land. Freestanding sea sponges are a bit more interesting. These sponges have more inner volume compared with their outside surface area and sometimes grow into strange shapes, often reaching gigantic proportions.
Many of the freestanding sponges are well known to most people. For example, nearly everyone has heard of the barrel sea sponge, a large tropical sponge that sometimes grows large enough to fit a whole person inside. Equally well known are the tube sponges of the tropics, coming in nearly every color of the rainbow.
While not all sea sponges are as colorful or as large as those found in the tropics, sponges are an ancient and efficient design, which will probably continue to populate the world's oceans longer than people will populate the Earth.
Famous Sea Sponges
The Tube Sponge is one of the most common varieties of sea sponge to be found on the reef. It is distinguished by its long tube-shaped growths, and ranges in color from purple to blue, gray, and gray-green. Filtered water is ejected through the large openings on the ends. This is one of the few reef invertebrates that is blue in color.
The Vase Sponge is a common species found in the Caribbean off the eastern coast of Florida. A large bell shape with a deep central cavity characterizes it. This sea sponge grows up to 2 feet wide and 3 feet high. It ranges in color from purple to red and brown, and is found attached to rocks near the sandy bottoms.
This small Yellow Sponge species is commonly found throughout the Pacific coastal waters of the United States. It is found growing in small colonies, and ranges in color from orange to bright yellow. This sea sponge and can be found encrusting rocks on the reef face.
Red Tree Sponge
This bright red sponge species is very common throughout the Caribbean Sea. This sea sponge usually grows to a height of about 8 inches. This is one species that is easy to keep and can do relatively well in a home aquarium environment. These sponges require a moderate water flow and dim light to do well.
Common Sea Squirt
This species of sea squirt is verry common on the reef, and is usually found in deep water. It can be found encrusting the rocks in large colonies. This squirt's leathery bag-like body has a white and gray or brown spotted exterior with a bright green interior. It is sometimes introduced into the aquarium on live rock.
The tunicates are very similar to sea squirts. They take water in through a large opening where nutrients are filtered out. The water is then expelled through another opening. Painted tunicates are about 3/4 inch long and commonly grow in colonies. They are found in translucent red, purple, and yellow colors.
Skin rash from sea sponges
Sea sponges produce a large variety of toxin, which are present, either on the surface of the sponge or released into the water. The intended function of these toxins is to ward off predators that would otherwise feed on the sponges, but humans can become the unintended targets by handling sponges or by abrading against sponges. Small particles from the sponge surface (spicules) may also dislodge and remain adherent to the skin surface of the unfortunate traveler causing local inflammation.
Symptoms of Sponge Toxins
Treatment of Skin injuries from Sponges
- Localized area of redness at the site of injury
- Tingling at the site of injury (paresthesia)
- Itching (puritis)
- Swelling (localized edema)
- Small raised areas may form (papules) which may go on to form small fluid-filled bumps (vesicles)
- Although less common, systemic symptoms of nausea, malaise, and fainting (syncope) have also been reported.
The above listed local reactions may be caused by either the sponge toxin itself or by an inflammatory reaction from the small sponge particles (spicules) that are adherent to the skin.
- Treat the affected area of the skin by applying a vinegar-soaked cloth for about 15 minutes. If you're out in the middle of nowhere and didn't bring any vinegar with you, your own urine will do in a pinch.
**NOTE: if you have a choice in the matter, use urine from a male, because male urine is consider more or less "sterile", females, are more prone to have occult urinary tract infections, and thus using female urine could introduce bacteria into the wound.
- Pat the skin dry with a nonabrasive cloth.
- Pat the skin with the sticky side of some adhesive tape to remove any fine particles (spicules) of sponge that may be present.
- Again soak the area with a vinegar soaked cloth for another 5 minutes.
- If the skin remains inflamed or itchy, you can apply over the counter
- Hydrocortisone cream 0.5% twice day the area for several days until the inflammation subsides.
- If symptoms persist for more that a three days seek medical attention.
Sea Sponges - Medical Research
The World Health Organization (WHO) estimates that 300 million to 500 million cases of malaria occur annually, mostly in developing countries near the equator, and that the disease claims a million lives a year. Tuberculosis infects about a third of the world's population and kills an estimated 3 million people each year.
Several sponge species e.g. Sigmosceptrella and Prianos produce compounds that show great promise as a drug to combat malaria, tuberculosis and other infectious diseases.
Many compounds extracted from sponges have also anti-viral, anti-neoplastic and anti-cancer properties. Back in the 1950s, chemists found compounds in a sponge in the waters off the coast of Florida that wound up as antiviral drugs Acyclovir (Zovirax®), to treat herpes, and Cytarabine (Cytosar®), to treat non-Hodgkin's lymphoma6.
Novartis Pharma AG licensed Discodermolide, a metabolite of the deep-sea sponge, Discodermia dissolute, discovered by Pomponi in the waters off the Bahamas, in 1998 for development as a candidate agent for treatment of cancers.
Halichondrin B, first isolated from the Japanese sponge Halichondria okadai, has shown promise in vivo as a treatment for melanoma and leukemia and is currently in pre-clinical trials at the NCI with material obtained from the New Zealand deep-water sponge Lissodendoryx.
Debromohymenialdisine (DBH), one of several constituents of the common Palauan shallow-water sponge Stylotella aurantium is an interesting druglike molecule that is easily synthesized and is being developed for treatment of osteoarthritis.
Sea Sponges - Biological and Economic Uses
Harvesting of sponges was once carried out by near-naked divers who were reputed to be able to dive to great depths while holding their breath for minutes at a time. Today sponges are harvested by hooking, harpooning in shallow waters, or by skin-diving.
Fossil evidence has led many scientists to believe sponges have remained relatively unchanged since around 500 million years ago. And, the way things are going; they will probably still inhabit the waters of the world long after all evidence of human occupation has gone.