wilhelmaresembles the proverbial `rolling stone' that stays at a given location if the conditions are favourable and starts moving when conditions change for the worse.Įarly work ( Edmondson, 1946)and later ( Fishelson, 1981)reported that species of the genus Tethya sp.
It is most likely that environmental conditions play an important roll in induction of movement. The movement track followed a straight direction for long periods, but directions could be altered instantly. The stability of the skeletal superstructure arrangement during movement suggests that only the cortical tissue is involved in movement, with only local tissue rearrangements. The overall morphology was stable, and skeletal rotation during movement was shown this is the first time that such movement has been demonstrated in a sponge.
wilhelmadisplays a unique mode of locomotion among sponges, without reorganizing the whole sponge body. wilhelma quantitatively on natural and artificial substrates, to test for a peristaltic movement mechanism and to check for the influence of morphological changes. The aims of the present study were to track T. wilhelmadisplays extraordinary movement and rhythmic body contractions, and is thus a valuable model for the investigation of sponge movement. This behaviour has been known for more almost 150 years, but it is only partly understood. Although sponges (Porifera) are basal Metazoa without muscles and a central nervous system, they are able to locomote, which is generally correlated to drastic morphological changes.
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