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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  
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)