Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help
Researched by | Jacqueline Hill | Refereed by | Prof. P. Geoff Moore |
Authority | (Montagu, 1808) | ||
Other common names | - | Synonyms | - |
A tube dwelling amphipod, elongate and rather flattened up to 13 mm in length. Colour varied, often yellow-grey with brown, red or black patches depending the colour of the surrounding habitat. Eyes small, round and dark.
- none -
Family | Ischyroceridae | |
Genus | Jassa | |
Authority | (Montagu, 1808) | |
Recent Synonyms |
Typical abundance | High density | ||
Male size range | 7-13mm | ||
Male size at maturity | 3.11-11.6mm | ||
Female size range | 3.8-6.6mm | ||
Female size at maturity | |||
Growth form | Articulate | ||
Growth rate | 0.07mm/day | ||
Body flexibility | High (greater than 45 degrees) | ||
Mobility | |||
Characteristic feeding method | Active suspension feeder, Predator, See additional information | ||
Diet/food source | See additional information | ||
Typically feeds on | Unselective suspension feeder of detritus and small organisms. | ||
Sociability | |||
Environmental position | Epibenthic | ||
Dependency | No information found. | ||
Supports | No information | ||
Is the species harmful? | No |
Physiographic preferences | Open coast, Strait / sound, Enclosed coast / Embayment |
Biological zone preferences | Lower eulittoral, Sublittoral fringe, Upper infralittoral |
Substratum / habitat preferences | Macroalgae, Artificial (man-made), Bedrock, Other species |
Tidal strength preferences | Moderately Strong 1 to 3 knots (0.5-1.5 m/sec.), Strong 3 to 6 knots (1.5-3 m/sec.) |
Wave exposure preferences | Exposed, Moderately exposed, Sheltered, Very exposed |
Salinity preferences | Full (30-40 psu) |
Depth range | See additional information. |
Other preferences | No text entered |
Migration Pattern | Non-migratory / resident |
Reproductive type | Gonochoristic (dioecious) | |
Reproductive frequency | Annual protracted | |
Fecundity (number of eggs) | 11-100 | |
Generation time | <1 year | |
Age at maturity | 2-6 months | |
Season | See additional text | |
Life span | <1 year |
Larval/propagule type | - |
Larval/juvenile development | Direct development |
Duration of larval stage | Not relevant |
Larval dispersal potential | No information |
Larval settlement period | Not relevant |
The MarLIN sensitivity assessment approach used below has been superseded by the MarESA (Marine Evidence-based Sensitivity Assessment) approach (see menu). The MarLIN approach was used for assessments from 1999-2010. The MarESA approach reflects the recent conservation imperatives and terminology and is used for sensitivity assessments from 2014 onwards.
Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
Intermediate | Moderate | Moderate | Very low | |
Substratum loss will remove the tubes in which Jassa falcata lives. Although the species is mobile it is a weak swimmer and so likely that only some individuals would escape and rebuild tubes elsewhere. However, Jassa falcata does not have a larval stage so dispersal potential is limited (Hughes, 1979) although rafting on algal debris is probably important in extending the species range (Moore, P.G., pers. comm.). In a New England sub-tidal zone for example, Jassa falcata recolonized areas of cleared rock within 4 months (Sebens, 1986). | ||||
Intermediate | Moderate | Moderate | Very low | |
Smothering of the population by sediment to a depth of 5cm above the substratum may completely cover Jassa falcata tubes and prevent suspension feeding. The species is likely to be able to crawl away from the sediment but as a poor swimmer and with the absence of a larval stage it has limited dispersal potential (Hughes, 1979). However, recolonization from adjacent populations can take place in less than a year and rafting on algal debris is probably important in extending the species range (Moore, P.G., pers. comm.). In a New England sub-tidal zone for example, Jassa falcata recolonized areas of cleared rock within 4 months (Sebens, 1986). | ||||
Low | High | Low | Very low | |
Jassa falcata is tolerant of high turbidity (Moore, 1973(b)) and uses debris in the construction of its tube and so is likely to be tolerant of siltation at the level of the benchmark, 100mg/l for a month. In investigations in France all Jassa falcata tubes on hydroids and algae were open at both ends (Conlan, 1989) and Moore (1977) speculates that this may be adaptive in avoiding siltation. | ||||
No information | ||||
Intermediate | High | Low | Very low | |
Bousfield (1973) suggests the tolerance of amphipods to desiccation is generally quite low. Jassa falcata has been observed fully exposed to air at low tide, though normally remaining within its tube (Conlan, 1989). Jassa falcata is a sub-tidal and lower shore species so an increase in desiccation at the level of the benchmark is likely to reduce the extent of the population. | ||||
Low | High | Low | Very low | |
Jassa falcata has been observed amongst red algae fully exposed to the air and so can tolerate some emergence. Some individuals were crawling amongst the tubes, but most remained within (Conlan, 1989). Increased emergence may decrease the upper limit of Jassa falcata populations, whereas decreases in emergence may allow the species to colonize further up the shore. | ||||
No information | ||||
Low | High | Low | Moderate | |
Jassa falcata is morphologically adapted to rough hydrodynamic environments since it is able to remain within its tube and its stout gnathopods can hold tightly to algae. Ebling et al. (1948) investigated the fauna of the Saccorhiza polyschides canopy at Lough Ine, Ireland with reference to water currents. Jassa falcata was abundant at all stations where current was strong (4-6 knots), occurred in small quantities in moderate current (2-3 knots) and was absent from all stations where current was weak (1 knot). Weak currents interfere with feeding and Jassa falcata is sometimes outcompeted in weak currents by another tube dwelling amphipod, Corophium insidiosum that is able to switch from suspension feeding to deposit feeding in low flow water rates. (Nair & Anger, 1980). | ||||
No information | ||||
Intermediate | Moderate | Moderate | Moderate | |
Jassa falcata occurs in temperatures from 1.5-27 °C in the Sea of Japan (Kamenskaya, 1977). Bousfield (1973), however, reports that amphipod tolerance to extremes of temperature is low. Life span, growth rates, size at maturity and fecundity are all affected by temperature. In Helgoland, hardly any individual growth was observed at temperatures of 2.5-4.4 °C and growth was rapid at maximal temperatures of about 17°C. Peak reproduction occurred at temperatures of 10-14 °C and egg numbers per gravid females were higher, 92-100 in summer months compared to about 10 eggs in winter (Nair & Anger, 1980). In laboratory investigation Jassa falcata showed a slow, long-continued growth at 10°C resulting in a prolonged life span and a larger final body size (Nair & Anger, 1979). Although growth and reproduction are influenced by temperature no information on upper or lower lethal temperature limit was found. | ||||
No information | ||||
Low | High | Low | Very low | |
In a study of kelp holdfast fauna in north east Britain, Moore (1973(b)) found Jassa falcata a ubiquitous species but with higher abundances in turbid waters. This species was also found to favour waters with high turbidity in Los Angeles - Long Beach harbours (Barnard, 1958) and was absent from clear waters. Mills (1967) suggested that turbidity of the water might be responsible for initiating feeding in some tube-dwelling amphipods. | ||||
No information | ||||
Low | High | Low | Low | |
Although found on most coasts around the UK, the density of Jassa falcata increases with greater wave exposure (Moore, 1985). With stout gnathopods Jassa falcata is adapted for rough hydrodynamic environments. | ||||
No information | ||||
Tolerant | Not relevant | Not sensitive | Very low | |
Jassa falcata often inhabits areas such as buoys and pilings in harbours where noise and vibration levels are likely to be high. It is likely therefore, that the species is tolerant of noise. | ||||
Tolerant | Not relevant | Not sensitive | Very low | |
Jassa falcata often inhabits areas such as buoys and pilings in harbours where visual disturbance at the level of the benchmark, continuous presence for one month of moving objects such as boats, commonly occurs and its visual acuity is probably low. It is likely therefore, that the species is not sensitive to visual disturbance. | ||||
Intermediate | High | Low | Very low | |
Abrasion at the level of the benchmark would be likely to kill or displace some individuals. However, since Jassa falcata lives in colonies the whole population may not be destroyed and so intolerance is assessed as intermediate. Recovery is good because recolonization from adjacent populations can take place within 4 months (Sebens, 1986). | ||||
Low | High | Low | Very low | |
Displacement may result in the death of loss of individuals, however if physically removed from their original position onto a suitable substratum Jassa falcata would be able to construct a new tube. In the absence of a larval stage dispersal of Jassa falcata normally occurs by short distance dispersal by juveniles so recolonization should be rapid. In a New England sublittoral community, for example, Jassa falcata recolonized areas of cleared rock within 4 months (Sebens, 1986). However, after the last moult silk spinning glands in males are reduced in size limiting the tube building ability of sexually mature adult males. |
Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
Intermediate | Moderate | Moderate | Very low | |
intolerance to some chemicals has been observed in amphipods. Gammaridean amphipods have been reported to be intolerant of TBT with 10 day LC50 (the concentration which produces 50% mortality) values of 1-48ng/l (Meador et al., 1993). Jassa falcata was absent from sites close to a bromide extraction plant releasing acidified halogenated effluent (Hoare & Hiscock, 1974). | ||||
Intermediate | Moderate | Moderate | Very low | |
Crustaceans are generally regarded to be sensitive to cadmium (McLusky et al., 1986). In laboratory investigations Hong & Reish (1987) observed 96hour LC50 (the concentration which produces 50% mortality) water column concentrations of between 0.19 and 1.83 mg/l for several species of amphipod. | ||||
High | Very High | High | ||
Amphipods in general are highly sensitive to oil pollution (Suchanek, 1983). After the Amoco Cadiz oil spill, for example, there was a reduction in both the number of amphipod species and the number of individuals (Cabioch et al., 1978). Eight years after the oil spill amphipod numbers had still not fully recovered (Dauvin, 1987). Analysis of kelp holfast fauna after the Sea Empress oil spill in Milford Haven showed an almost complete lack of any amphipods at the badly oiled sites, while large numbers of Jassa falcata were present at unaffected sites (SEEEC, 1998). | ||||
No information | No information | No information | Not relevant | |
Insufficient information. | ||||
No information | No information | No information | Not relevant | |
In a study of amphipods in north east Britain Jassa falcata was found to prefer turbid waters, in particular those unpolluted by industrial and domestic waste including sewage (Moore, 1973(b)). However, in other studies of sites polluted with industrial and sewage waste Jassa falcata was more abundant (Bellan-Santini, 1980). Information about the exact nature of the pollution is not available and so an assessment of intolerance to nutrients is not possible. | ||||
No information | No information | No information | Not relevant | |
At moorings, buoys and piers in the Sea of Japan Jassa falcata was the dominant species at salinities of 30-33psu but at lower salinities Corophiidae were more abundant (Kamenskaya, 1977). Therefore, at lower salinities there may be increased risk of competition from other tube-building amphipods. | ||||
No information | ||||
High | High | Moderate | Moderate | |
In a survey of Los Angeles to Long Beach harbours Jassa falcata was absent from areas of low oxygen concentration (0-2.5mg/l). However, recovery was rapid with recolonization taking place within 6-9 months (Barnard, 1958). |
Intolerance | Recoverability | Sensitivity | Evidence/Confidence | |
No information | No information | No information | Not relevant | |
Insufficient information. | ||||
No information | No information | No information | Not relevant | |
Insufficient information. | ||||
Intermediate | High | Low | Very low | |
Recovery from extraction of 50% of individuals is likely to be good because Jassa falcata reproduces all year round. Recolonization from existing individuals in the same area can take place within less than one year (Barnard, 1958). In New England, Jassa falcata had recolonized areas of cleared subtidal rock within 1-4 months (Sebens, 1986). | ||||
Intermediate | High | Low | Very low | |
Laminaria spp. used by the amphipod as substratum may be harvested for commercial use. Epiphytic or holdfast populations may be lost or displaced. However, a protracted reproductive period means that successful recruitment and recolonization from adjacent populations is likely. In New England, for example, Jassa falcata recolonized areas of cleared rock within 4 months (Sebens, 1986). |
- no data -
National (GB) importance | - | Global red list (IUCN) category | - |
Native | - | ||
Origin | - | Date Arrived | - |
Baardseth, E., 1970. Synopsis of the biological data on knotted wrack Ascophyllum nodosum (L.) Le Jolis. FAO Fisheries Synopsis, no. 38, Rev. 1.
Barnard, J.L., 1958. Amphipod crustaceans as fouling organisms in Los Angeles-Long Beach harbours, with reference to the influence of seawater turbidity. California Fish and Game, 44, 161-170.
Barnes, R.D., 1980. Invertebrate Zoology, 4th ed. Philadelphia: Holt-Saunders International Editions.
Bellan-Santini, D., 1980. Relationship between populations of amphipods and pollution. Marine Pollution Bulletin, 11, 224-227. https://doi.org/10.1016/0025-326X(80)90411-7
Bieler, R., 1992. Gastropod phylogeny and systematics. Annual Review of Ecology and Systematics, 23, 311 -338.
Bousfield, E.L., 1973. Shallow-water gammaridean Amphipoda of New England. London: Cornell University Press.
Cabioch, L., Dauvin, J.C. & Gentil, F., 1978. Preliminary observations on pollution of the sea bed and disturbance of sub-littoral communities in northern Brittany by oil from the Amoco Cadiz. Marine Pollution Bulletin, 9, 303-307.
Conlan, K.E., 1989. Delayed reproduction and adult dimorphism in males of the amphipod genus Jassa (Corophioidea: Ischyroceridae): an explanation for systematic confusion. Journal of Crustacean Biology, 9, 601-625.
Conlan, K.E., 1990. Revision of the crustacean amphipod genus Jassa Leach (Corophioidea: Ischyroceridae). Canadian Journal of Zoology, 68, 2031-2075.
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Ebling, F.J., Kitching, J.A., Purchon, R.D. & Bassingdale, R., 1948. The ecology of Lough Ine rapids with special reference to water currents. 2. The fauna of the Saccorhiza canopy. Journal of Animal Ecology, 17, 223-244.
Fish, J.D. & Fish, S., 1996. A student's guide to the seashore. Cambridge: Cambridge University Press.
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Hoare, R. & Hiscock, K., 1974. An ecological survey of the rocky coast adjacent to the effluent of a bromine extraction plant. Estuarine and Coastal Marine Science, 2 (4), 329-348.
Hong, J. & Reish, D.J., 1987. Acute toxicity of cadmium to eight species of marine amphipod and isopod crustaceans from southern California. Bulletin of Environmental Contamination and Toxicology, 39, 884-888.
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Hughes, R.G., 1979. The dispersal and dispersion of some epizoites of the hydroid Nemertesia antennina (L.) Journal of the Marine Biological Association of the United Kingdom, 59, 879-887.
Kamenskaya, O.E., 1977. Amphipods in the fouling of hydrotechnical installations in the sea of Japan. Soviet Journal of Marine Biology, 3, 375-379.
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Meador, J.P., Varanasi, U. & Krone, C.A., 1993. Differential sensitivity of marine infaunal amphipods to tributyltin. Marine Biology, 116, 231-239.
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Moore, P.G., 1985. Levels of heterogeneity and the amphipod fauna of kelp holdfasts. In The Ecology of Rocky Coasts: essays presented to J.R. Lewis, D.Sc. (ed. P.G. Moore & R. Seed), 274-289. London: Hodder & Stoughton Ltd.
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Nair, K.K.C. & Anger, K., 1980. Seasonal variation in population structure and biochemical composition of Jassa falcata (Crustacea, Amphipoda) off the island of Helgoland (North Sea). Estuarine and Coastal Marine Science, 11, 505-513.
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OBIS (Ocean Biodiversity Information System), 2023. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. www.iobis.org. Accessed: 2023-06-07
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This review can be cited as:
Last Updated: 08/08/2000