Order CYDIPPIDA Lesson, 1843

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Introduction

Members of the Cydippida are generally regarded as primitive, as species of Platyctenida, Ganeshida, Lobata and Cestida (and probably Thalassoca) have developmental stages resembling adult cydippids. Many described cydippid species may actually be larval stages of other orders. Included in this category are the problematic genera Lobocrypta, Paracelsia, Thoe and Tizardia.

The six families of Cydippida may be divided into two major groups: those with tentacle sheaths opening aborally above the level of the infundibulum (Pleurobrachiidae, Mertensiidae, Euplokamididae), and those with tentacle sheaths opening orally below the level of the infundibulum (Haeckeliidae, Lampeidae, Bathyctenidae). Members of the second group often have tentacles without side branches and widely everpharynxes, suggesting that they feed on larger prey than the first group. Species in the second group are too poorly known to determine whether this division has phylogenetic significance. From Harbison & Madin 1982.

Currently, Pleurobrachiidae is the only family reported from Australian waters. However, one of the commonest ctenophores in Australian waters appears to belong to a new family in the Cydippida. This new species differs from all others in numerous characters and is recorded from the seas of NT, QLD, SA. WA (Gershwin pers. comm.).

Diagnosis

Pelagic ctenophores with the paired primary tentaretractile into tentacle sheaths; the comb rows are well developed. The general body shape is globular or ovoid; some forms are greatly flattened in the stomodaeal plane. The meridional canals end blindly; the paragastric canals (when present) end blindly at the mouth.

Diagnosis References

Harbison, G.R. & Madin, L.P. 1982. Ctenophora. 707-715, pls 68-69 in Parker, S.P. (ed.). Taxonomy and Classification of Living Organisms. New York : McGraw-Hill Vol. 1. [708]

General References

Harbison, G.R. & Madin, L.P. 1982. Ctenophora. 707-715, pls 68-69 in Parker, S.P. (ed.). Taxonomy and Classification of Living Organisms. New York : McGraw-Hill Vol. 1.

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