Life in the Open Ocean. Joseph J. Torres
forward swimming, where the nectophores contract in a less coordinated fashion, producing a forward velocity of 8–10 cm s−1. Sometimes the nectophores on each side of a column contract rhythmically to produce a side‐to‐side forward movement.
3 Reverse swimming, usually resulting from a stimulation to the float. In this case contraction of muscles at the velar openings directs the jet anteriorly, propelling the siphonophore to the rear.
Table 3.7 Abundance of siphonophores relative to other gelatinous zooplankton, estimated primarily by direct observation.
Source: Mackie et al. (1987), table 17 (pp. 242–243), with the permission of Academic Press (Elsevier).
| Location | Siphonophores | Medusae | Ctenophores | Method | References | |
|---|---|---|---|---|---|---|
| Gulf of Mexico (no./10 000 m3) | Physonects | Calycophorans | ||||
| Spring (4)a | 2.0 ± 3.4 | 0 | 1.7 ± 2.2 | 10.2 ± 9.9 | Grid | Biggs et al. (1984) |
| Summer (8) | 0 | 0 | 0 | 0 | Grid | Biggs et al. (1984) |
| Fall (11)b | 8.8 ± 7.1 | <0.8 ± 1.0 | <8.7 ± 20.7 | 36.6 ± 51.0 | Grid | Biggs et al. (1984) |
| Winter (8)c | 4.1 ± 2.3 | 2.6 ± 2.1 | 3.4 ± 3.5 | 31.2 ± 53.8 | Grid | Biggs et al. (1984) |
| North Atlantic (no./10 000 m3) | Total | Calycophorans | ||||
| Temperate (4) | 15.2 ± 24.5 | 27%d | 14.2 ± 13.4 | 38.5 ± 31.9 | Grid | Biggs et al. (1981) |
| Transitional (6) | 6.2 ± 10.4 | 62%d | 11.5 ± 9.7 | 24.7 ± 36.1 | Grid | Biggs et al. (1981) |
| Subtropical (7) | 8.0 ± 4.5 | 90%dd | 2.6 ± 3.0 | 2.1 ± 3.2 | Grid | Biggs et al. (1981) |
| Bahamas (no./10 000 m3) | Total 8.3 ± 13.1 | 9.0 ± 7.8 | 52.3 ± 59.9 | Grid | Biggs et al. (1981) | |
| Southern California (no./m3) | Polygastric | Eudoxids | ||||
| Sphaeronectes gracilis | 8.3 ± 4.6 | 6.3 ± 5.4 | 4.6 ± 1.7 | 2.5 ± 1.5 | Net | Purcell and Kremer (1983) |
| Muggiaea atlantica | 6.7 ± 3.7 | 17.3 ± 11.5 | 4.6 ± 1.7 | 2.5 ± 1.5 | Net | Purcell and Kremer (1983) |
| Apolemia sp. at 450 m | 0.2 ± 0.02 | — | 0.06 | 0.05 ± 0.02 | Submersible | Alldredge et al. (1984) |
| Strait of Georgia (no./m3) | Polygastric | Eudoxids | ||||
| Muggiaea atlantica (October) | 1.4 ± 0.8 | 8.0 ± 3.8 | 0.7 ± 0.5 | 0.1 ± 0.2 | Net | Purcell (1982) |
| Muggiaea atlantica (November) | 2.7 ± 1.8 | 7.2 ± 4.1 | 1.4 | 0.08 | Net | Mackie and Mills (1983) |
| Muggiaea atlantica (November) | 2.0 ± 2.6 | Common | 2.9–10 | 0.8–5.5 | Submersible | Mackie and Mills (1983) |