Starfish, often called sea stars, are marine invertebrates. A common question about their feeding habits is whether they bite. Starfish do not possess the anatomical structures necessary to bite. They lack jaws, teeth, and musculature for such an action. Their biology involves a distinct method of consuming food, which does not include biting.
Their Physical Structure
Starfish exhibit a radial body plan, typically with five arms extending from a central disk, though some species may have more arms. Their mouth is located on the underside of their central disk, also known as the oral surface. Unlike many other animals, starfish do not have teeth for chewing.
Their hard, spiny skin is supported by an endoskeleton made of small, calcareous elements called ossicles. These ossicles provide rigidity and protection, forming a lattice-like structure of calcium carbonate. Starfish also have thousands of tube feet on their underside, which are essential for movement, gripping surfaces, and handling prey. These tube feet operate using a hydraulic water vascular system, allowing them to exert pressure but not to bite.
How Starfish Consume Food
Starfish employ a unique feeding strategy. Many species use a process called stomach eversion. When feeding, they can push a portion of their cardiac stomach out through their mouth and onto their prey. This everted stomach then wraps around the food, and digestive enzymes are secreted directly onto the prey for external digestion.
This method enables starfish to consume prey much larger than their mouth opening, such as bivalves like clams, mussels, and oysters. Once the prey’s tissues are liquefied into a mixture, the starfish retracts its stomach back into its body, where further digestion and nutrient absorption occur. Some primitive starfish, however, swallow their prey whole and then expel indigestible parts. Starfish are opportunistic feeders, with diets including various invertebrates, detritus, and even coral polyps for some species.
Starfish and Human Contact
Starfish are generally not considered dangerous to humans. Most species are harmless, and their spines are not harmful to humans. However, some species, such as the Crown-of-Thorns starfish, possess venomous spines that can cause painful stings. These stings can lead to pain, swelling, and discomfort, though they are usually not life-threatening.
Observe starfish in their natural habitat without touching them. Removing starfish from the water can cause them stress and suffocation, as they rely on water for respiration. Human skin oils or sunscreens can also be detrimental to these delicate marine animals.