Animal mesoderm forms by enterocoelic pouching, through invagination of the endoderm. The main deuterostome phyla are the Echinodermata and the Chordata. Echinoderms are exclusively marine and include starfish, sea urchins, and sea cucumbers. The chordates are dominated by the vertebrates (animals with backbones), which consist of fishes, amphibians, reptiles, birds, and mammals. The deuterostomes also include the Hemichordata (acorn worms). The Ecdysozoa are protostomes, named after their shared trait of ecdysis, growth by moulting. They include the largest animal phylum, the Arthropoda, which contains insects, spiders, crabs, and their kin. All of these have a body divided into repeating segments, typically
Stichodactyla toxin Stichodactyla toxin Stichodactyla toxin (ShK) is a 35-residue basic peptide from the sea anemone "Stichodactyla helianthus" that blocks a number of potassium channels. An analogue of ShK called ShK-186 or Dalazatide is in human trials as a therapeutic for autoimmune diseases. "Stichodactyla helianthus" is a species of sea anemone (Phylum: Cnidaria) belonging to the family "Stichodactylidae". "Helianthus" comes from the Greek words helios meaning sun, and anthos meaning flower, which corresponds to the species' common name "sun anemone". It is sessile and uses potent neurotoxins for defense against its primary predator, the spiny lobster. The venom contains, among other components,