More than 2200 species of the wild flora and fauna photographed in Zihuatanejo, Guerrero, Mexico and the surrounding area.
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Tunicates of Zihuatanejo
SUBPHYLUM TUNICATA
-Tunicates (Subphylum Tunicata)
-Sea Squirts (Class Ascidiacea)
Ascidiacea is a class of marine invertebrates commonly known as sea squirts, belonging to the subphylum Tunicata. Although their adult form is sac-like and simple, ascidians are chordates and possess a notochord and dorsal nerve cord during their free-swimming larval stage. Adults are typically sessile, attached to rocks, docks, mangroves, or other submerged surfaces, and are enclosed in a protective outer covering called a tunic, composed largely of a cellulose-like substance known as tunicin. They feed by drawing water in through an incurrent siphon, filtering out plankton and organic particles with a specialized pharyngeal basket, and expelling the water through an excurrent siphon—hence the name “sea squirt” when water is expelled upon disturbance.
Description
• Ascidiacea is a class of marine invertebrates in the subphylum Tunicata, commonly known as sea squirts. Adults are usually sac-shaped and attach to rocks, coral, shells, docks, or other submerged surfaces. Their bodies are covered by a protective outer layer called a tunic and typically have two openings: an inhalant siphon that draws water in and an exhalant siphon that expels it. Although adults appear simple, their larvae have a notochord, a defining characteristic shared with other chordates.
Range
• Ascidiacea occurs in marine environments worldwide, from tropical coastal waters to polar seas and from shallow intertidal zones to the deep ocean. Sea squirts are found in the waters of Zihuatanejo, Guerrero, and the surrounding area.
Habitat
• Sea squirts commonly inhabit rocky shores, coral reefs, seagrass beds, mangroves, harbours, and other submerged habitats. Most adult species attach to hard surfaces, either living individually or forming colonies. Some species also grow on shells, submerged vegetation, and artificial structures.
Diet
• Ascidiacea are primarily filter feeders. They draw seawater through the inhalant siphon and use a mucus-covered pharyngeal basket to capture bacteria, microscopic plankton, and suspended organic particles. Filtered water is then expelled through the exhalant siphon.
Sea Squirt
Ascidiacea (Class)
