''Ptilometra australis'', the passion flower feather star, is a species of crinoid. It is native to the coasts of southeastern Australia where it is found on reefs, in estuaries and bays at depths down to about .

Description

The passion flower feather star is a robust crinoid with a diameter of about when fully extended. It has eighteen to twenty jointed arms which can be coiled up when the animal is not feeding. These are attached to a cup-shaped body or

calyx Calyx or calyce (plural "calyces"), from the Latin ''calix'' which itself comes from the Ancient Greek ''κάλυξ'' (''kálux'') meaning "husk" or "pod", may refer to: Biology * Calyx (anatomy), collective name for several cup-like structures ...

. The arms are edged by feathery appendages known as pinnules. Each pinnule has rows of tube feet on either side of a central ambulacral groove lined with

cilia The cilium, plural cilia (), is a membrane-bound organelle found on most types of eukaryotic cell, and certain microorganisms known as ciliates. Cilia are absent in bacteria and archaea. The cilium has the shape of a slender threadlike projecti ...

. This groove is continuous with the central groove on the arm which leads to the mouth at the centre of the calyx. The aboral (lower) surface of the crinoid has a number of hooked appendages called

cirri Giovanni Battista Cirri (1 October 1724 – 11 June 1808) was an Italian cellist and composer in the 18th century. Biography Cirri was born in Forlì in the Emilia-Romagna Region of Italy. He had his first musical training with his brother ...

which grip onto the

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (locomotion), the surface over which an organism lo ...

, which may be a rock, a sponge, a coral or sea fan. The colour of this crinoid is usually some shade of red, though subjection to organic solvents yields a complex mixture of pigments whose components can be separated using chromatography.

Distribution and habitat

The passion flower feather star is native to the coasts of southeastern Australia down to depths of about . Its range extends from

Masthead Island Masthead Island is a coral cay located in the southern Great Barrier Reef, 60 kilometres northeast of Gladstone, Queensland. The island is a protected area and forms part of Capricornia Cays National Park. Masthead Island is one of the most u ...

in Queensland and the mouth of the Clarence River in New South Wales to

Port Philip Bay Port Phillip (Kulin languages, Kulin: ''Narm-Narm'') or Port Phillip Bay is a horsehead-shaped bay#Types, enclosed bay on the central coast of southern Victoria (Australia), Victoria, Australia. The bay opens into the Bass Strait via a short, ...

in Victoria. It is found on rocks and rubble in sheltered bays, in estuaries and on reefs.

Biology

The passion flower feather star is a

filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

. It catches plankton and suspended particles of

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

with the tube feet on the pinnules. These feet are covered with sticky mucus that traps the food particles and then roll it into balls before moving them into the ambulacral groove, where cilia propel the stream of mucus towards the mouth.

References

{{Taxonbar, from=Q2449473 Comatulida Animals described in 1843 Fauna of the Pacific Ocean