Pyura fissa is a species of tunicate, commonly known as a sea squirt, belonging to the family Pyuridae. It is a filter feeder found in intertidal and subtidal zones along the coasts of the southeastern Atlantic Ocean, with its distribution extending from South Africa to Namibia.
Description & Characteristics
Pyura fissa exhibits a distinctive, elongated, cylindrical body shape, typically reaching a maximum length of 10 centimeters. The outer surface of the body is covered in a thick, leathery tunic, which may be smooth or rough depending on the individual. The color of the tunic varies from pale yellow to reddish-brown, often with patches of green or black pigmentation. The tunic is perforated with numerous small pores called siphons, which allow water to flow in and out of the animal’s body for feeding and respiration.
Habitat and Occurrence
Pyura fissa is an intertidal and subtidal species, commonly found attached to rocks, shells, and other hard substrates. It is particularly abundant in rocky shores exposed to wave action, often forming dense aggregations. The species thrives in the temperate waters of the southeastern Atlantic Ocean, ranging from the intertidal zone down to depths of 100 meters. It is frequently encountered in the infralittoral zone, the area between the lowest low tide mark and the depth where seaweed growth is still prevalent.
Taxonomy
Pyura fissa is classified within the phylum Chordata, belonging to the subphylum Tunicata. It is placed in the Class: Ascidiacea, an extensive group of mostly sessile filter-feeding marine invertebrates. Further categorized within the Order: Stolidobranchia, a group characterized by their simple internal structure and siphon arrangement, Pyura fissa is part of the Family: Pyuridae, a family that encompasses various species of sea squirts known for their leathery tunics.
Feeding
Pyura fissa is a filter feeder, relying on the continuous flow of seawater through its siphons to capture microscopic food particles. The water enters the body through the inhalant siphon, passing over a mucus-coated sieve-like structure called a branchial sac. As water flows through the branchial sac, microscopic plankton, algae, and other organic matter are trapped in the mucus and transported to the animal’s mouth. The filtered water then exits the body through the exhalant siphon. Pyura fissa, like other sea squirts, plays a vital role in marine ecosystems by contributing to the cycling of nutrients and the removal of particulate organic matter from the water column.
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