Hemichordata is a phylum which consists of triploblastic, enterocoelomate, and bilaterally symmetrical marine deuterostome animals, generally considered the sister group of the echinoderms. They appear in the Lower or Middle Cambrian and include two main classes: Enteropneusta, and Pterobranchia. A third class, Planctosphaeroidea, is known only from the larva of a single species, Planctosphaera pelagica. The class Graptolithina, formerly considered extinct, is now placed within the pterobranchs, represented by a single living genus Rhabdopleura.
Barnacles are a type of arthropod constituting the subclass Cirripedia in the subphylum Crustacea, and are hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. Around 1,000 barnacle species are currently known.
Intertidal ecology is the study of intertidal ecosystems, where organisms live between the low and high tide lines. At low tide, the intertidal is exposed whereas at high tide, the intertidal is underwater. Intertidal ecologists therefore study the interactions between intertidal organisms and their environment, as well as between different species of intertidal organisms within a particular intertidal community. The most important environmental and species interactions may vary based on the type of intertidal community being studied, the broadest of classifications being based on substrates—rocky shore and soft bottom communities.
Joan Roughgarden is an American ecologist and evolutionary biologist. She has engaged in theory and observation of coevolution and competition in Anolis lizards of the Caribbean, and recruitment limitation in the rocky intertidal zones of California and Oregon. She has more recently become known for her rejection of sexual selection, her theistic evolutionism, and her work on holobiont evolution.
Austrominius modestus is a species of barnacle in the family Elminiidae, native to Australia, Tasmania and New Zealand, but now spread to Britain and the north west coasts of Europe. It reaches a maximum size of about 10 millimetres in diameter.
The Chthamalidae are a family of chthamaloid barnacles, living entirely in intertidal/subtidal habitats, characterized by a primary shell wall of eight, six, or four plates, lacking imbricating plate whorls, and either membraneous or more rarely calcareous basis. They are not found below immediate subtidal habitats, and more likely are found in the highest tier of shallow-water barnacle fauna. They can be found in the most rigorous wave-washed locations, and some species are found in the surf zone above high tide mark, only receiving water from wave action at high tide.
Gilvossius tyrrhenus is a species of thalassinidean crustacean which grows to a length of 70 mm (2.8 in). It lives in burrows in shallow sandy parts of the sea-bed in the Mediterranean Sea and northern Atlantic Ocean. It is the most common thalassinidean in the Mediterranean, and has been used as bait by fishermen for at least 200 years.
Acorn barnacle and acorn shell are vernacular names for certain types of stalkless barnacles, generally excluding stalked or gooseneck barnacles. As adults they are typically cone-shaped, symmetrical, and attached to rocks or other fixed objects in the ocean. Members of the barnacle order Balanomorpha are often called acorn barnacles.
Semibalanus balanoides is a common and widespread boreo-arctic species of acorn barnacle. It is common on rocks and other substrates in the intertidal zone of north-western Europe and both coasts of North America.
Megabalanus is a genus of barnacles in the family Balanidae. Members of the genus grow to 7 cm (2.8 in) in length and inhabit the lower intertidal zone.
Chthamalus is a genus of barnacles that is found along almost all non-boreal coasts of the northern hemisphere, as well as many regions in the southern hemisphere. These small barnacles have been studied in part because of the taxonomic confusion over a group of species that, by and large, are morphologically and ecologically quite similar. In recent years, molecular techniques have identified a number of cryptic species that have been subsequently confirmed by taxonomists using morphological measurements. Most recently the genus has been shown to be paraphyletic, with the genus Microeuraphia nested within Chthamalus.
Chthamalus stellatus, common name Poli's stellate barnacle, is a species of acorn barnacle common on rocky shores in South West England, Ireland, and Southern Europe. It is named after Giuseppe Saverio Poli.
Pollicipes pollicipes, known as the goose neck barnacle, goose barnacle or leaf barnacle is a species of goose barnacle, also well known under the taxonomic synonym Pollicipes cornucopia. It is closely related to Pollicipes polymerus, a species with the same common names, but found on the Pacific coast of North America, and to Pollicipes elegans a species from the coast of Chile. It is found on rocky shores in the north-east Atlantic Ocean and is prized as a delicacy, especially in the Iberian Peninsula.
Patella ferruginea, commonly known as the ferruginous limpet is a species of true limpet, a marine gastropod mollusk in the family Patellidae. It is a large limpet, endemic to the western Mediterranean Sea, and although common in the past, it is now rare and restricted to only a few locations.
Hemioniscus balani, a species of isopod crustacean, is a widespread parasitic castrator of barnacle in the northern Atlantic Ocean. Its range extends from Norway to the Atlantic coast of France, and as far west as Massachusetts. It is also commonly found on the Pacific coast of North America; it is not known if the Pacific and Atlantic populations are the same species, or if the Pacific population exists following human-assisted introduction.
Balanus crenatus is a species of acorn barnacle in the Balanidae family. It is found in the North Pacific and the North Atlantic Ocean.
Amphibalanus amphitrite is a species of acorn barnacle in the Balanidae family. Its common names include the striped barnacle, the purple acorn barnacle and Amphitrite's rock barnacle. It is found in warm and temperate waters worldwide.
Chthamalus anisopoma is a species of intertidal barnacle. Indigenous to the northern Gulf of California, adult Chthamalus anisopoma are found on exposed shores between 0.0 and 2.0 m above mean low tide. The species is typically absent in areas protected from wave splash. Notably, Chthamalus anisipoma exhibits predator-mediated plasticity in the growth of its calcareous test. In the presence of the carnivorous gastropod Acanthina angelica, the barnacle's typical conical growth form is altered to appear bent over, with the operculum perpendicular to the substrate. The alternate form is more resistant to predation.
Chthamalus fragilis is a small gray barnacle found in the upper intertidal zone of the northwestern Atlantic Ocean, from approximately Cape Cod southward to Florida and into the Caribbean and Gulf of Mexico. It is also commonly known as little grey barnacle. The species is believed to have been distributed only as far northward as North Carolina or Virginia until the late 1800s, when it was noticed along the Massachusetts coast. The species may have expanded its range naturally or been introduced to New England through anthropogenic activities. Chthamalus fragilis is unusual in that it often recruits to stems of Spartina alterniflora.
Acrocnida is a genus of brittle stars in the family Amphiuridae. The genus contains three members: Acrocnida brachiata, Acrocnida semisquamata, and Acrocnida spatulispina. There has also been observed hybridization between both Acrocnida brachiata and Acrocnida spatulispina. It is a fairly common genus, usually found along the coasts of Northwestern Europe, but with some species like semisquamata appearing around West Africa. Members of this genus primarily prefer intertidal and sub-tidal habitats, and they are they are less likely to be found in intertidal areas by comparison. This genus was not officially classified until 1926, by T. Gislén. One study found that due to the increased calcification that Acrocnida brachiata causes could be a potential source of Carbon Dioxide for not only the warm, shallow environments they live in, but also for the atmosphere.
