(A) During a brief larval phase, C. intestinalis (dorsal is top) finds and attaches to a substrate via its anterior adhesive palps (two of three are shown), where it initiates metamorphosis. The larva swims using a muscular tail, aided by the rigidity and stiffness of the notochord, a hollow tube within the tail. The pigmented brain organs, the ocellus and otolith, which sense light and gravity, help to guide the animal. (B) A C. intestinalis adult has two siphons, oral and atrial, positioned opposite the attachment point (arrowheads); the flow of water in and out is indicated (blue arrows). C. intestinalis are hermaphrodites, and here the egg and sperm ducts are visible; both sperm and eggs exit via the atrial siphon cavity. (C) Clusters of C. intestinalis attached to the underside of a kayak in Santa Barbara, California. These marine invaders often line vessel hulls and crowd submerged ropes, buoys and other surfaces. (D) A confocal projection of the brain and spinal cord of C. intestinalis near hatching stage; anterior is right. C. intestinalis is ideal for imaging and, unlike its larger chordate cousins, large portions of the animal can be imaged within a single field of view. Cell membranes are in green (etr>ArcLight) and nuclei in red (etr>RFP). Image credits: (A, B, D), M Kourakis; (C), S Abdul-Wajid.