The Marine Life Information Network

Information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Mobility and attachment type

Sessile Non-motile; permanently attached at the base (Lincoln et al., 1998) (e.g. cup corals).
Mobile Capable of movement from one location to another.
Temporary attachment Temporary / sporadic attachment. Attached to a substratum but capable of movement across (or through) it (i.e. sedentary) (e.g. sea anemones).
An organism that moves through the water column via movements of its cilia, flagella, fins, legs or appendages, via undulatory movements of the body or via jet propulsion (e.g. fish, squid).
Cilia/ Flagella Swimming is efected by beating of cilia and/or flagella (includes the fused cilia of Ctenophores).
Muscular contraction (body length) Swimming is effected by muscular contractions along the length of the body, which may be aided by body protrusions or strucutures (e.g. parapodia, fins).
Appendages (paddles) Swimming is effected one or more pairs of appendages (legs or paddles) e.g. the pleiopods of Isopod, Amphipod or Decapod crustaceans, or the legs of amphibians and vertebrates.
Jet propulsion Swimming is effected by contraction of the body or body cavity to produce a 'jet' of water, e.g. medusae and cephalopods (from Barnes et al., 2006).
Glider An organism that is able to glide through the air (e.g. using some form of membrane or airfoil) but cannot propel itself through the air (e.g flying fish).
An organism whose movement is dependent on wind or water currents (e.g. by-the-wind sailors, jellyfish).
Passive drifter Movement dependant on wind or water currents
Bysso-pelagic Use of a length of byssus thread (e.g. micro-molluscs, juvenile molluscs) or mucus (e.g Nemertesia planaulae) to be carried by water flow.
Ballooning/Kiting Use of a length of silk to be carried by the wind (e.g. spiders).
Jumper/Hopper Organisms able to undertake a rapid jump or hop several times their own body length, using specialized limbs or appendages (e.g. sand hoppers, spring tails, grass hoppers etc).
Creeper An organism that slowly moves or 'creeps' along the surface of the substratum, e.g. snails and slugs. 
Crawler/Walker/Climber An organism that moves along or across the substratum via movements of its legs, appendages or muscles (e.g. crabs).
Burrower An organism that moves through the substratum by burrowing (e.g. earthworms, polychaetes).


  • Barnes R.S.K., Calow P., Olive P.J.W., Golding, D.W, and Spicer, J.I. (2006). The invertebrates: a new synthesis, 3rd edn. Oxford: Blackwell Science Ltd.
  • Lincoln, R., Boxshall, G. & Clark, P., 1998. A dictionary of ecology, evolution and systematics. Cambridge: Cambridge University of Press.