Florida manatees are large, gentle marine mammals inhabiting the state’s coastal waters, rivers, and springs. These aquatic herbivores, often called “sea cows,” graze entirely on plants found in both fresh and saltwater environments.
Primary Aquatic Vegetation
Seagrasses form the primary component of the Florida manatee’s diet. These underwater flowering plants grow in shallow, clear coastal waters, creating extensive meadows that are a staple food source. Manatees consume all seven species of seagrass found in Florida waters, including turtle grass (Thalassia testudinum), manatee grass (Syringodium filiforme), and shoal grass (Halodule wrightii). These seagrass beds are vital for manatee nutrition.
Seagrasses provide essential nutrients and energy that support the manatee’s substantial body mass. The health and abundance of these underwater meadows directly influence manatee survival. Unfortunately, seagrass habitats have faced significant decline in some areas, impacting manatee populations.
Other Plant-Based Foods
While seagrasses are a main food source, manatees also consume a variety of other plants, especially in freshwater environments. These include hydrilla, water hyacinth, water lettuce, alligator weed, eelgrass, coontail, pickerelweed, water celery, and musk grass. These plants supplement their diet.
Manatees are adaptable foragers and also consume various types of algae. Occasionally, they might eat mangrove leaves or fallen acorns. These diverse sources allow them to utilize available vegetation in different habitats.
How Manatees Graze
Manatees use specialized methods to gather their plant-based diet. They use their large, prehensile lips to grasp and tear vegetation. Each side of their split upper lip can move independently, manipulating plants into their mouths. Their front flippers also assist in pulling plants or digging for roots.
Once gathered, vegetation is processed by horny, ridged pads at the front of their palate and lower jaw, which break food into smaller pieces. Molars then grind the fibrous material. Manatees consume a substantial amount of food, typically 10-15% of their body weight daily (100 to 150 pounds for an average adult). This large intake requires them to spend 6 to 8 hours each day feeding. Manatees also require access to fresh water, often obtained from plants or by seeking freshwater sources.
Harmful Ingestions
Accidental ingestion of non-food items or human food poses threats to manatees. Feeding them human food, such as lettuce, can lead to nutritional deficiencies because it does not provide the necessary nutrients found in their natural diet. This practice can also cause manatees to associate humans with food, altering their natural foraging behaviors and potentially making them dependent on handouts. Such dependency can put them in harm’s way, as they may approach boats expecting food and risk injury.
Marine debris, including plastic bags, fishing lines, and other trash, presents a danger to manatees. Manatees can accidentally ingest these items while grazing, leading to blockages in their digestive tracts, which can result in starvation or even death. Studies have shown that a notable percentage of manatee necropsies reveal ingested marine debris, with fishing gear being a common culprit. These ingestions highlight the impact of human activities on manatee health.