Tetragonioides

Tetragonioides is a genus of sea spiders, also known as pycnogonids, belonging to the family Ammotheidae. These marine arthropods are characterized by their elongated bodies and extremely long, slender legs. The genus Tetragonioides contains several species, all of which are found in the Antarctic region. These sea spiders are typically found on the seabed, where they move slowly across the substrate. Their diet consists primarily of cnidarians, such as hydroids and anemones, which they pierce with their proboscis to extract nutrients. Tetragonioides species exhibit a remarkable degree of sexual dimorphism, with males often possessing significantly larger ovigers, which are modified appendages used for carrying egg masses. Reproduction in Tetragonioides, as with most pycnogonids, involves the male brooding the eggs until they hatch into protonymphons, a larval stage that is often parasitic on other marine invertebrates. The precise ecological role of Tetragonioides within Antarctic benthic communities is still an area of ongoing research, but they are considered a component of the local food web.