Movement Siphonophores use a method of
locomotion similar to jet propulsion. A siphonophore is a complex aggregate colony made up of many nectophores, which are clonal individuals that form by
budding and are genetically identical. Depending on where each individual nectophore is positioned within the siphonophore, their function differs. The velum becomes smaller and more circular during times of forward propulsion compared to a large velum that is seen during refill periods. Their diets consist of a variety of
copepods, other small crustaceans, cnidarians,
ctenophores, and small fish. Some siphonophores, such as
Praya dubia, have been observed to feed on other species in the same order. Generally, the diets of strong swimming siphonophores consist of smaller prey, and the diets of weak swimming siphonophores consist of larger prey. Research has shown that specific diets vary even between different individuals of the same species depending on their particular environment. A majority of siphonophores have
gastrozooids that have a characteristic tentacle attached to the base of the zooid. This structural feature functions in assisting the organisms in catching prey. The nematocysts then shoot millions The gelatinous body plan allows for flexibility when catching prey, but the gelatinous adaptations are based on habitat. They swim around waiting for their long tentacles to encounter prey. In addition, siphonophores in a group denoted
Erenna have the ability to generate
bioluminescence and red fluorescence while its tentilla twitches in a way to mimic motions of small crustaceans and copepods. These actions entice the prey to move closer to the siphonophore, allowing it to trap and digest it. Predators of Siphonophores include
narcomedusae,
gastropods, other siphonophores, and large fish such as
Mola mola. This species then proceeds to undergo "blanching," and emit a startlingly bright light.
Nanomia, among other siphonophore species, can move both forward and backwards to escape a stimulus from the opposite side, using their nectophores for propulsion. While there are few observations of defensive behavior
in situ, it is argued that these strategies help siphonophores evade predators. There is limited research on the mechanistic release of eudoxid fragments for reproduction, and studies are determining whether to consider them as clustered communities or individuals. Recent research has identified eudoxid tissue remodeling before release by a specified muscle, as well as a dispersal mechanism that temporarily alters siphonophore buoyancy.
Bioluminescence Nearly all siphonophores have bioluminescent capabilities. Since these organisms are extremely fragile, they are rarely observed alive. Bioluminescence in siphonophores has been thought to have evolved as a defense mechanism. Siphonophores of the
deep-sea genus
Erenna (found at depths between ) are thought to use their
bioluminescent capability for offense too, as a lure to attract fish. This genus is one of the few to prey on fish rather than crustaceans. The bioluminescent organs, called
tentilla, on these non-visual individuals emit red
fluorescence along with a rhythmic flicking pattern, which attracts prey as it resembles smaller organisms such as
zooplankton and
copepods. Thus, it has been concluded that they use luminescence as a lure to attract prey. Some research indicates that deep-sea organisms can not detect long wavelengths, and red light has a long wavelength of 680 nm. If this is the case, then fish are not lured by
Erenna, and there must be another explanation. However, the deep-sea remains largely unexplored and red light sensitivity in fish such as
Cyclothone and the deep
myctophid fish should not be discarded. Bioluminescent lures are found in many different species of siphonophores, and are used for a variety of reasons. Species such as
Agalma okeni, Athorybia rosacea, Athorybia lucida, and
Lychnafalma utricularia use their lures as a mimicry device to attract prey.
A. rosacea mimic fish larvae,
A. lucida are thought to mimic larvacean houses, and
L. utricularia mimic hydromedusa. The species
Resomia ornicephala uses their green and blue fluorescing tentilla to attract krill, helping them to outcompete other organisms that are hunting for the same prey.
Erenna sirena uses bioluminescent lures surrounded by red fluorescence to attract prey and possibly mimic a fish from the
Cyclothone genus. Their prey is lured in through a unique flicking behavior associated with the tentilla. When young, the tentilla of organisms in the
Erenna genus contain only bioluminescent tissue, but, as the organism ages, red fluorescent material is also present in these tissues. ==Taxonomy==