pennátusok

Pennátusok, commonly known as feather stars or sea lilies, are a group of marine invertebrates belonging to the class Crinoidea. They are closely related to starfish and sea urchins but possess distinct characteristics that set them apart. Unlike their sessile relatives, many pennatúsk species are free-moving, though some remain attached to the seabed. Their name derives from the Latin *penna*, meaning "feather," in reference to their elongated, feather-like arms.

Feather stars are typically found in shallow to deep ocean environments worldwide, thriving in both tropical and temperate waters. They exhibit a wide range of sizes, from small species measuring a few centimeters to larger ones reaching up to 60 centimeters in arm span. Their bodies consist of a central disk, or calyx, from which multiple branching arms extend. These arms are covered in tube feet, which aid in locomotion, feeding, and respiration.

Pennatúsk primarily feed on plankton and small particles, using their arms to capture food from the water column. Some species can detach their arms to escape predators or regenerate lost parts. Reproduction varies among species, with some releasing gametes into the water for external fertilization, while others exhibit more complex reproductive strategies.

Ecologically, pennatúsk play a role in maintaining marine biodiversity by serving as both prey and habitat for various organisms. They are also indicators of ocean health, as their presence or absence can reflect changes in water quality and ecosystem stability. Due to their sensitivity to environmental disturbances, some species are considered vulnerable and face conservation concerns.

While often mistaken for sea lilies (a related but distinct group), pennatúsk are distinct in their mobility and feeding habits. They are a fascinating example of marine adaptation, showcasing the diversity of life in the ocean.