Whale feces, the excrement of whales, has a significant role in the ecology of the oceans, and whales have been referred to as "marine ecosystem engineers". Nitrogen released by cetacean species and iron chelate is a significant benefit to the marine food chain in addition to sequestering carbon for long periods. Whale feces can give information on a number of aspects of the health, natural history and ecology of an animal or group as it contains DNA, hormones, toxins, and other chemicals. In addition to feces, the digestive system of sperm whales produces ambergris, a solid, waxy, flammable substance of a dull grey or blackish color which can be found floating on the sea or washed up on the coast. Description Whales excrete plumes of liquid feces which are flocculent in nature, i.e., consisting of "a loose aggregation of particles, fluffy or woolly in nature". The feces may contain undigested hard objects such as the beaks of squids. The feces may be ejected underwater but comes to the surface where it floats until it disassociates.Fecal samples are observed by color, odor, texture, and buoyancy. The fecal samples may appear green-brownish, fishy smelling, lots of mucus and mostly floating. Flatulence has been recorded in whales. The feces of krill-eating whales is red in colour because krill is rich in iron. Ecological significance Cetaceans are an important source of nitrogen circulation in the ocean. A study in the Gulf of Maine extrapolated from modern levels nitrogen recycling in the sea due to marine mammals, such as cetaceans and seals, prior to the advent of commercial culling, estimating a former level thrice that of supply of nitrogen fixed from the atmosphere. Even today, despite reduction of marine mammal populations and increase in nitrogen uptake from the atmosphere and nitrogen pollution, the local clustering of marine mammals plays a significant role in maintaining the productivity in the regions they frequent. The enrichment is not only in primary productivity but also secondary productivity in the form of abundance in fish populations. The study assumes that whales tend to defecate more commonly in the upper part of the water column, which they frequent for breathing; additionally the feces tend to float. Whales feed at deeper levels of the ocean where krill is found. The fecal action of whales thus reverses the usual flow of nutrients of the ocean's "biological pump" due to the downward flow of