Common heart urchin
The common heart urchin, also referred to as the sea potato, is a marine echinoderm characterized by its heart-shaped shell covered with long, light brown spines that resemble fur. This species is typically found buried in sandy or muddy environments along coastlines in temperate regions, including parts of the southeastern United States, eastern South America, western Europe and Africa, as well as Japan, Australia, and New Zealand. Measuring up to four inches (10 centimeters) in length, the heart urchin utilizes its spines to burrow into the substrate, moving slowly to sift through sand and gather food particles.
The heart urchin employs tube feet, which are tiny, tube-like structures on its shell, for feeding rather than movement. It consumes a variety of organic matter, including sand, relying on its digestive system to extract nutrients. Reproduction occurs through external fertilization, where eggs and sperm are released into the water, resulting in larvae that drift and develop before settling on the seabed. While not directly threatened by human activity, heart urchins face risks from environmental pollutants like oil spills and chemical leaks, although they are currently not classified as a threatened species.
On this Page
Subject Terms
Heart urchin
The common heart urchin, also known as the sea potato, is a spiny-skinned creature. Its heart-shaped shell is thickly covered with long, light brown spines which appear more like fur than rough spikes. It can be found in the temperate waters of the world's oceans.
Kingdom: Animalia
Phylum: Echinodermata
Class: Echinoidea
Order: Spatangoidea
Family: Loveniidae
Genus: Echinocardium
Species: Cordatum
The common heart urchin is usually found buried in sandy or muddy beaches. It is often found along the coasts of the southeastern United States, eastern South America, the western coasts of Europe and Africa, the coasts of Japan, and the coasts of Australia and New Zealand.
The common heart urchin burrows into the sand or mud by the use of its long, sandy spines. Typically, it burrows straight down until it is at a depth of two to eight inches (five to 20 centimeters). It then inches its way forward very slowly moving the sand and silt, or muddy sand, toward the rear end of its body. Generally, all of the common heart urchin's spines point in the same direction to aid in the process of burrowing.
The full-grown adult common heart urchin reaches a maximum length of about four inches (10 centimeters). As its name suggests, the common heart urchin has a heart-shaped test, or hard, protective outer shell. The common heart urchin's test is mostly covered with long, sand-colored spines, but also bears tiny, tube-like tentacles called tube feet. Although starfish and spiny sea urchins use their tube feet for movement, the common heart urchin uses its tube feet to help it gather food from the sand.
There are two places on the common heart urchin's body which are not covered. Those two places are the mouth and the hole it uses to adjust the water in its body. The opening which adjusts the water level in the common heart urchin's body is necessary for the movement of the tube feet.
As the common heart urchin moves along the beach, it feeds on the many particles of living organisms which collect in pools along muddy beaches. Unlike some animals which filter their food before putting it inside their bodies, the common heart urchin eats everything, including the sand, and relies on its digestive system to sort out the nutritional value of its meals.
During the midsummer the common heart urchin releases its eggs or sperm into the water. Once in the water, the eggs are fertilized and begin developing into tiny common heart urchin larvae. This process of external fertilization is known as spawning. The fertilized eggs drift through the surface levels of the water feeding on tiny microscopic organisms. Most larval common heart urchins are eaten by predators such as fish. Stingrays, sea stars, and turles may also prey on common heart urchins. The surviving common heart urchin larvae settle to the seabed in the area below the low tide mark. There they change into adult common heart urchins. Some die from poor beach habitats.
The life span of the common heart urchin is not known. Although this creature is not directly harmed by humans, it does suffer from oil spills, chemical leaks, and other beach pollutants. However, the common heart urchin is not a threatened species.
Bibliography
“Echinocardium Cordatum.” World Register of Marine Species, 2024, www.marinespecies.org/aphia.php?p=taxdetails&id=124392. Accessed 6 Apr. 2024.
“Waikīkī Aquarium - Heart Urchin - Echinoderms.” Waikiki Aquarium, www.waikikiaquarium.org/experience/animal-guide/invertebrates/echinoderms/heart-urchin. Accessed 6 Apr. 2024.