Shells
"A Field Guide to Australian Shells"
Live Pearl shell at Gantheaume Point (photo bk)
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Tectus fenestratus (latticed top shell) photo John Slattery |
| The ruby murex shell (chicoreus rubuginosus) is only found in the Broome region at Riddell beach - it is protected and very endangered. |
MUREX SHELLS
Muricidae, the largest family among the marine snails, have extremely variable shells.All are active predators and tropical or semi-tropical in habitat. Most have radulas adapted for tearing flesh and capable of drilling. However, for most, chipping away the edges of a clam shell is preferred to boring. In borers, an accessory boring organ secretes a calcium chelating compound that softens a shell during the drilling process,as do also the Naticidae. Drilling is then carried out by the radula. The paralytic agent that the most muricids use for killing is a neurotoxic mucus secretion of the hypobranchial gland. Oddly enough, this secretion also turns up in several entirely unrelated gastropod families. The mucus secretion, particularly from the Thaiidinae (see below), has been used also by people of antiquity, to manufacture a remarkably stable purple dye (Monfils, 2001).
Muricidae is a large and varied family of small to large predatory sea snails, marine gastropod mollusks, commonly known as murex snails or rock snails. With about 1,600 living species, the Muricidae represent almost 10% of the Neogastropoda. Additionally, 1,200 fossil species have been recognized.[1] Numerous subfamilies are recognized, although experts disagree about the subfamily divisions and the definitions of the genera. Many muricids have unusual shells which are considered attractive by shell collectorsand by interior designers. Shell description Muricid shells are variably shaped, generally with a raised spire and strong sculpture with spiral ridges also frequently bearing spines, tubercles, or blade-like processes. Life habits Most species of muricids are carnivorous, active predators that feed on other gastropods, bivalves, and barnacles. The access to the soft parts of the prey is typically obtained by boring a hole through the shell by means of a softening secretion and the scraping action of the radula. Because of their carnivory, some species may be considered pests because they can cause considerable destruction both in exploited natural beds of bivalves, and in farmed areas of commercial bivalves. Muricids lay eggs in protective, corneous capsules, the size and shape of which vary by species. From these capsules the crawling juveniles, or more rarely planktonic larvae, hatch. The fossil record The family Muricidae first appears in the fossil record during the Aptian age of the Cretaceous period. |
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Live olive shell - photo courtesy Taryn Ryan |
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Razorfish, Razor shell or Razor clam (photo bk) The fan-shaped clams, which are also known as razorfish, can grow up to 50 centimetres long. They bury themselves in sand, leaving sharp, upward-facing shell edges exposed. The razor shell lives under the sand, using its powerful foot to dig to a safe depth. The razor shell also squirts water down into the sand, removing loose sand from its path. The foot is thought to exert a pressure of about 196 kilopascals. |
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Cowry Shell (photo: Rebecca Hayes) |
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Live Tiger Cowry Shell with it's mantle out - (Sharmaine Donnelly-Chorlton) |
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A Baler shell and
its egg case. Each of those little pockets will have a baby baler shell (photo Shannon Elizabeth Halvorsen) |
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| Cyparea (Zoila) decipiens ... and found "between North West Cape and Buccaneer Archipelago" and moderately common (Perry Benjamin found on Cable Beach) |
Cone Shells
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https://www.youtube.com/watch?v=I2kbdl1P2PI The Cone Shell is a sub tropical and tropical gastropod with venomous harpoon-like bard which pokes through the narrow end of the shell. Do not touch. Can cause temporary paralysis and breathing difficulties leading to death within six hours. (photo Australian Museum) Perry Benjamin The commonly found cone shell in Broome under the rocks at low tide is Conus victoriae ... found in a variety of colours ... brown, green ... often in pairs with their eggs hanging from the covering rock ... best left alone as you don't want to be the who when stung who has more than mild effects. There has been more than 16 fatalities recorded from cone stings, 12 from C. geographus as in BK's photo found in sand under coral. Although I haven't found any in Broome at low tide doesn't mean they're not there. Perry Benjamin All cone shells have a sting ... as explained below the pictured shell is C. geographus whose sting has caused 12 recorded deaths ... if you must pick up a cone do so by the larger end with 2 fingers only ... hand away from the shell ... as the barb exits from the narrow end other. |
Conch and Baler Shells
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| The Mala (syrinx aruanus – conch shell). Binyga (Melo amphora - baler shell) were collected by Aboriginal people and kept to be used for carrying water and as a digging utensil. |
Mud Cockles
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| Mud cockles - Jirrinygiliny (Anadara granosa) |
In the mangroves, when the Jirrinygiliny (Anadara granosa) - mud cockles are fat the women collect, wash and cook them on the coals or boil them.
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| Heart cockle Lunulicardia retusa (photo Dianne Bennett) |
Oysters
When the Janga (oyster from the Ostreide family) are fat they are collected from the rocks.
They are collected within their shells and cooked on the coals.
The shell is then cracked open and the Janga eaten. Nowadays, the Janga may be collected without its shell and boiled.
