Search results
Results from the WOW.Com Content Network
Front view of land snail showing upper and lower sets of tentacles Abalone showing pallial tentacles. Many molluscs have tentacles of one form or another. The most familiar are those of the pulmonate land snails, which usually have two sets of tentacles on the head: when extended the upper pair have eyes at their tips; the lower pair are chemoreceptors.
There are two sets of ocular tentacles: one set in front of the eye (pre-ocular) and one set behind the eye (post-ocular). The digital and labial tentacles are arrayed circularly around the mouth, with the digital tentacles forming the outermost ring and the labial tentacles in between the digital tentacles and the mouth.
In terrestrial pulmonate gastropods, eye spots are present at the tips of the tentacles in the Stylommatophora or at the base of the tentacles in the Basommatophora.These eye spots range from simple ocelli that cannot project an image (simply distinguishing light and dark), to more complex pit and even lens eyes. [6]
Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks [a] (/ ˈ m ɒ l ə s k s /). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda . [ 5 ]
As soft-bodied cephalopods, they lack the external shell of most molluscs, including other cephalopods like the nautiloids and the extinct Ammonoidea. [131] They have eight limbs like other Coleoidea, but lack the extra specialised feeding appendages known as tentacles which are longer and thinner with suckers only at their club-like ends. [132]
The creatures have been six and 11 tentacles, researchers said. The newfound, brown-colored creatures are extremely diminutive in size, measuring less than a millimeter wide, researchers said.
The new species of jellyfish is considered “relatively large,” its body reaching just over 1 inch in height and its tentacles measuring over 2 inches in length, the study said.
It has a circular body shape and about 240 tentacles. Its most distinctive feature is its bright red, “cross-shaped” stomach. Photos show the St. George’s cross medusa jellyfish in an aquarium.