Starfish, also known as sea stars, are captivating marine invertebrates that pique curiosity due to their distinctive shapes and diverse presence across the world’s oceans. These creatures, belonging to the class Asteroidea, are not fish, but rather echinoderms, sharing a lineage with sea urchins and sand dollars. A common point of interest surrounding these animals is how long they live, a question with answers as varied as the species themselves.
How Long Do Starfish Typically Live?
The lifespan of a starfish can vary. On average, many starfish species can live for about 35 years in their natural habitats. For example, the ochre sea star (Pisaster ochraceus), a common species along the Pacific coast of North America, typically lives between 4 and 20 years, with some individuals reaching up to 34 years. In contrast, the sunflower sea star (Pycnopodia helianthoides), one of the largest sea stars, generally has an average lifespan of 5 to 7.5 years, though some have been recorded living as long as 65 years.
What Influences a Starfish’s Lifespan?
Several external and environmental factors influence a starfish’s longevity. The quality of their habitat, such as pollution, water temperature, and salinity, directly affects their health and survival. Extreme temperature fluctuations and low oxygen levels, for instance, can significantly shorten a starfish’s life. The availability of food also supports their growth and physiological functions. While starfish have few natural predators like gulls or sea otters, they can be preyed upon by crabs, some fish, and other starfish. Disease, such as sea star wasting disease, has caused significant declines in populations, leading to rapid mortality. Human activities, including habitat destruction, pollution, and the impacts of climate change, also pose threats to starfish populations and their lifespans.
Unique Traits Contributing to Starfish Lifespan
Starfish possess biological adaptations that contribute to their resilience and lifespans. Their most recognized trait is regeneration, the ability to regrow lost arms or, in some cases, an entire body from a single arm, provided a portion of the central disc is present. This capability allows them to survive injuries from predators or environmental damage. Their decentralized nervous system, without a centralized brain, contributes to their ability to sense light, touch, and react to their environment through a network of nerves distributed throughout their body, allowing them to function if parts are damaged. Some species exhibit a relatively slow metabolic rate, which reduces the accumulation of cellular damage over time. Starfish also employ various defense mechanisms, including tough, often spiny skin, or the release of chemicals called saponins to deter predators. Some species produce large amounts of repellent mucus or possess toxins for protection.