Under Construction
This is an archived version of a Tree of Life page. For up-to-date information, please refer to the current version of this page.

Pterotracheidae

Roger R. Seapy
taxon links [down<--]Carinarioidea Interpreting the tree
close box

This tree diagram shows the relationships between several groups of organisms.

The root of the current tree connects the organisms featured in this tree to their containing group and the rest of the Tree of Life. The basal branching point in the tree represents the ancestor of the other groups in the tree. This ancestor diversified over time into several descendent subgroups, which are represented as internal nodes and terminal taxa to the right.

example of a tree diagram

You can click on the root to travel down the Tree of Life all the way to the root of all Life, and you can click on the names of descendent subgroups to travel up the Tree of Life all the way to individual species.

For more information on ToL tree formatting, please see Interpreting the Tree or Classification. To learn more about phylogenetic trees, please visit our Phylogenetic Biology pages.

close box
Containing group: Carinarioidea

Introduction

All pterotracheids lack a shell as adults, although they possess one as larvae (the shell is shed at metamorphosis). Their bodies are elongate and basically cylindrical, consisting of a proboscis, trunk and tail. The maximal recorded body length is 33 cm. The head lacks tentacles anterior to the eyes, except in male Firoloida. The viscera are compacted into a fusiform visceral nucleus. The swimming fin is large, located about midway between the anterior and posterior ends of the trunk, and bears a sucker only in males (presumably used in mating). Pterotracheids are mostly epipelagic (dwelling in the upper several hundred meters of the water column), although the vertical ranges of two species of Pterotrachea extend into the mesopelagic. Nocturnal vertical migration is seen in Pterotrachea.

The Pterotracheidae are widely regarded as the most highly derived of the heteropod families. Features supporting this contention include: (1) enlargement, elongation and narrowing (to a  basically cylindrical shape) of the body in the anterior-posterior axis, resulting in a streamlined body with enhanced swimming abilities, (2) shedding of the larval shell at metamorphosis, with the result that buoyancy problems are reduced since a calcareous shell (present in the adults of the other two families) is lacking, (3) compaction of the viscera into a pyriform visceral nucleus, which is largely enveloped by the gelatinous body at the posterior end of the trunk.

Diagnosis

Heteropod molluscs with:

Characteristics

  1. Shell
    1. Present in larvae
    2. Cast off at metamorphosis
  2. Body morphology
    1. Elongate, basically cylindrical; streamlined for rapid swimming
    2. Proboscis, trunk and tail body regions
       image info

      Figure. Body regions in Pterotrachea coronata.

    3. Viscera compacted into pyriform visceral nucleus
    4. Esophagus elongated, connecting buccal mass with visceral nucleus
       image info

      Figure. Location of esophagus in Pterotrachea coronata

  3. Swimming fin
    1. Located about midway between head region and visceral nucleus
    2. Fin sucker small; present only in males
       image info

      FigurePterotrachea coronata.  Left: swimming fin in female. Right:  swimming fin sucker in male.

  4. Head
    1. Shape of eye (in dorsal view) rectangular to triangular
    2.  image info

      Figure. Dorsal views of Pterotrachea eyes. Left: P. coronata adult. Middle: P. hippocampus juvenile. Right: P. hippocampus adult.

    3. Tentacles absent, except in Firoloida males
  5. Radula
    1. 24-30 tooth rows
    2. Rachidian (central) tooth polycuspid with prominent central cusp

Comments

Two genera are included in the Pterotracheidae, one of which, Firoloida, is monotypic. The genera can be distinguished by the following characters:

Genus Tail Posterior egg string or filamentous extension Tentacles
Pterotrachea prominent absent absent in both sexes
Firoloida very short, ventral present present in males

References

Lalli, C. M. and R. W. Gilmer. 1989. Pelagic snails. The biology of holoplanktonic gastropod mollusks. Stanford Unive. Press, Stanford, pp. 1-259.

Richter, G. and R. R. Seapy. 1999. Heteropoda, pp. 621-647. In: D. Boltovskoy (ed.), South Atlantic Zooplankton. Leiden: Backhuys Publ.

Spoel, S. van der, L. Newman and K. W. Estep. 1997. Pelagic molluscs of the world. World Biodiversity Database, CD-ROM Series. Expert Center for Taxonomic Identification (ETI), Amsterdam, The Netherlands, UNESCO, Paris.

Tesch, J. J. 1949. Heteropoda. Dana Rep., 34: 1-54.

Title Illustrations
Scientific Name Pterotrachea coronata
Location Hawaiian Islands
Specimen Condition Live Specimen
View left side
Copyright ©
About This Page

Roger R. Seapy
California State University, Fullerton, California, USA

Correspondence regarding this page should be directed to Roger R. Seapy at

Citing this page:

Seapy, Roger R. . 2006. Pterotracheidae. Version 30 May 2006 (under construction). http://tolweb.org/Pterotracheidae/28734/2006.05.30 in The Tree of Life Web Project, http://tolweb.org

close box

This page is a Tree of Life Branch Page.

Each ToL branch page provides a synopsis of the characteristics of a group of organisms representing a branch of the Tree of Life. The major distinction between a branch and a leaf of the Tree of Life is that each branch can be further subdivided into descendent branches, that is, subgroups representing distinct genetic lineages.

For a more detailed explanation of the different ToL page types, have a look at the Structure of the Tree of Life page.

close box

Pterotracheidae

Page Content

articles & notes

Treehouses

people

Explore Other Groups

random page

  go to the Tree of Life home page
top