Dugongs, along with other sirenians, are referred to as "sea cows" because their diet consists mainly of sea-grass. When eating they ingest the whole plant, including the roots,[11] although when this is impossible they will feed on just the leaves.[5] A wide variety of seagrass has been found in dugong stomach contents, and evidence exists they will eat algae when seagrass is scarce.[12] Although almost completely herbivorous,[13] they will occasionally eat invertebrates such as jellyfish, sea squirts, and shellfish.[11] Dugongs in Moreton Bay, Australia, are omnivorous, feeding on invertebrates such as polychaetes[51] or marine algae when the supply of their choice grasses decreases. In other southern areas of both western and eastern Australia, there is evidence that dugongs actively seek out large invertebrates. This does not apply to dugongs in tropical areas, in which faecal evidence indicates that invertebrates are not eaten.[5]
Most dugongs do not feed from lush areas, but where the seagrass is more sparse. Additional factors such as protein concentration and regenerative ability also affect the value of a seagrass bed.[11] The chemical structure and composition of the seagrass is important, and the grass species most often eaten are low in fibre, high in nitrogen, and easily digestible.[5] In the Great Barrier Reef, dugongs feed on low-fibre high-nitrogen seagrass such as Halophila and Halodule,[11] so as to maximize nutrient intake instead of bulk eating. Seagrasses of a lower seral are preferred, where the area has not fully vegetated. Only certain seagrass meadows are suitable for dugong consumption, due to the dugong's highly specialised diet. There is evidence that dugongs actively alter seagrass species compositions at local levels. Dugongs may search out deeper seagrass. Feeding trails have been observed as deep as 33 metres (108 ft), and dugongs have been seen feeding as deep as 37 metres (121 ft).[5] Dugongs are relatively slow moving, swimming at around 10 kilometres per hour (6.2 mph).[48] When moving along the seabed to feed they walk on their pectoral fins.[16]
Due to their poor eyesight, dugongs often use smell to locate edible plants. They also have a strong tactile sense, and feel their surroundings with their long sensitive bristles.[13] They will dig up an entire plant and then shake it to remove the sand before eating it. They have been known to collect a pile of plants in one area before eating them.[16] The flexible and muscular upper lip is used to dig out the plants. This leaves furrows in the sand in their path.[13]
Dugongs, along with other sirenians, are referred to as "sea cows" because their diet consists mainly of sea-grass. When eating they ingest the whole plant, including the roots,[11] although when this is impossible they will feed on just the leaves.[5] A wide variety of seagrass has been found in dugong stomach contents, and evidence exists they will eat algae when seagrass is scarce.[12] Although almost completely herbivorous,[13] they will occasionally eat invertebrates such as jellyfish, sea squirts, and shellfish.[11] Dugongs in Moreton Bay, Australia, are omnivorous, feeding on invertebrates such as polychaetes[51] or marine algae when the supply of their choice grasses decreases. In other southern areas of both western and eastern Australia, there is evidence that dugongs actively seek out large invertebrates. This does not apply to dugongs in tropical areas, in which faecal evidence indicates that invertebrates are not eaten.[5]Most dugongs do not feed from lush areas, but where the seagrass is more sparse. Additional factors such as protein concentration and regenerative ability also affect the value of a seagrass bed.[11] The chemical structure and composition of the seagrass is important, and the grass species most often eaten are low in fibre, high in nitrogen, and easily digestible.[5] In the Great Barrier Reef, dugongs feed on low-fibre high-nitrogen seagrass such as Halophila and Halodule,[11] so as to maximize nutrient intake instead of bulk eating. Seagrasses of a lower seral are preferred, where the area has not fully vegetated. Only certain seagrass meadows are suitable for dugong consumption, due to the dugong's highly specialised diet. There is evidence that dugongs actively alter seagrass species compositions at local levels. Dugongs may search out deeper seagrass. Feeding trails have been observed as deep as 33 metres (108 ft), and dugongs have been seen feeding as deep as 37 metres (121 ft).[5] Dugongs are relatively slow moving, swimming at around 10 kilometres per hour (6.2 mph).[48] When moving along the seabed to feed they walk on their pectoral fins.[16]Due to their poor eyesight, dugongs often use smell to locate edible plants. They also have a strong tactile sense, and feel their surroundings with their long sensitive bristles.[13] They will dig up an entire plant and then shake it to remove the sand before eating it. They have been known to collect a pile of plants in one area before eating them.[16] The flexible and muscular upper lip is used to dig out the plants. This leaves furrows in the sand in their path.[13]
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