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How are pyrosomes different from salps and dolioloids?
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tunicate
Blue spot sea squirt (Clavelina moluccensis), a colonial tunicate.
Within the class Thaliacea, pyrosomes are distinguished from salps and dolioloids primarily by their colonial structure and evolutionary history.12
- Colonial Structure: Pyrosomes form long, tubular colonies in which the individual zooids are embedded within a tube that is open at one end. In contrast, both salps and dolioloids occur as either solitary individuals or as chains.13
- Evolutionary Distinctness: Pyrosomes are thought to have branched off first within the class Thaliacea and may not be closely related to the other two groups. Their structure resembles that of certain colonial ascidians, suggesting they may have evolved from attached colonies.21
- Reproductive Cycles: While salps and dolioloids are characterized by complex alternation of generations between solitary and colonial phases, the unique colonial arrangement of pyrosomes defines their primary mode of existence.13