Holdfast (hohld’-fast) In marine biology terms, structures with which sessile organisms’ such as kelp attach themselves to a solid substrate.
Sessile (ses’-il, -ahy) Permanently attached by the base, not able to move about.
Substrate (suhb’-streyt) A surface that serves as a base for a sessile marine organism. As in, “a larva looks for a substrate on which to settle.”
Stipe (stahyp’) The stem of an algae organism, most often used with reference to larger varieties such as kelp and seaweeds.
Blade (bleyd’) The “leaf” of an algae organism, usually used with kelp and seaweeds.