Table 1 Glossary of technical terminology
From: Life cycle evolution: was the eumetazoan ancestor a holopelagic, planktotrophic gastraea?
Phylogenetic terms | Developmental types | Larval types |
|---|---|---|
|  | (see also Figure 2) |  |
clade (monophyletic group) - an ancestor and all its living and extinct descendents | direct development - development without a larval stage | gastrula - hypothetic ancestor (gastraea) and early developmental stage of many neuralians, consisting of ecto- and endoderm |
apomorphy (advanced character) - a new character (state) at a node on the phylogenetic tree | indirect development (also called biphasic life cycle, including pelago-benthic life cycle) - development with a larval stage | ephyra - newly strobilated scyphozoan medusa |
trochaea - hypothetic protostomian ancestor, a gastrula with an archaeotroch, i.e., a peri-blastoporal ring of compound cilia (see Figure 11) | ||
trochophora - typical larva of spiralians with downstream-collecting ciliary bands (see Figures 5 and 6) | ||
plesiomorphy (primitive character) - a character (state) inherited from an earlier node on the tree | lecithotrophic - larva nourished exclusively by yolk | Â |
cyphonautes - planktotrophic larva of bryozoans with ciliary sieving | ||
planktotrophic - larva feeding in the plankton | actinotrocha - larva of phoronids with tentacles with ciliary sieving | |
facultative feeding – larva which may feed in the plankton, but which can develop normally without feeding | dipleurula - typical larva of ambulacrarians with perioral band of single cilia with upstream-collecting by ciliary reversal; the larvae of the echinoderm classes have special names (see Figure 9) | |
homoplasy (convergence) - apparently similar structures evolved independently in different clades | ||
|  | poecilogony - various developmental types in the same species | tornaria - dipleurula larva of enteropneusts with a perianal band of compound cilia used in swimming (see Figure 9) |