#858 - 863 - A Bunch of Invertebrates from a Halls Head Beach
#858 - Panulirus cygnus - Western Rock Lobster
The genus is Panulirus - the family is Palinuridae. That’s because half the genera in the family are anagrams of Palinurus.
The basis of Australia’s most valuable fishery - almost A$250 million back in 2004 - making up 20% of value of Australia’s total fishing economy. The fishery is strictly controlled, which is the main reason that it might actually be sustainable.
I found the empty forequarters of this one on the beach at Halls Head.
#859 - Physalia utriculus - Indo-Pacific Portuguese Man-o-War - Bluebottle
A familiar sight on most Australian beaches, especially after strong winds have blown flotillas of them ashore. The sail on top of the float may be left or righthanded, which is useful since that way any prevailing winds will only blow half the flotilla ashore when they’re sailing down the coast.
Unlike the Portuguese Man-o-War (P. physalis) of the Atlantic, P. utriculus has a single large fishing tentacle, and a smaller float. Physalia are colonial siphonophores, the individual animals specializing into the float, tentacles, gonads and digestive organ, and bound so close together that they can’t survive on their own. The stinging cells, however, can still be potent weeks after they wash ashore.
Advice for swimming when bluebottles are about -Wear protective clothing such as a lycra top, skivvy or stinger suit. This is a good idea anyway, as they’ll protect you from UV burns too.
First Aid
Also, try not to inhale any tentacles, should you swim face-first into one.
#858 - Janthina sp. - Purple Bubble-raft Snail
A very unusual snail, often washed up in the same weather that brings Bluebottles ashore. That’s because they share the same habitat - floating around on the surface of the ocean.
Adult Janthina can’t swim - if they lose their grip on the air-filled chitin bubbles they’ll sink to their death in the ocean depths. Until then, they’ll float around eating any suitable prey - the surface-dwelling hydroid colony known as the By-the-wind-Sailor Velella velella is a particular favorite.
Janthina is also counter shaded - the part facing the surface is a darker purple than the side facing down. This is useful counter shading, making them harder to spot by predators above the water and below.
#859 - Turbo sp. - Turban Snail
This is a fossilised Turban Snail, one of many in the incredibly fossil-rich pockets of the limestone outcropping on the beach at Halls Head. The limestone isn’t that old, and by the looks of things all these fossil shells got added to the mix when cavities got eroded in the rock by changing sea levels, filled up with snails and big chunks of coral, became cemented together, and then got exposed again as sea levels dropped once more.
There’s at least two species of Turban Snail living in the waters off Perth today - it’s entirely possible this is one of them.
The Turbinidae originated back in the Permian, 298-250 myo. They’re often large, and have a calcareous operculum to seal the shell entrance when predators threaten. There were a lot of opercula in among the fossils as well.
Species of Turbo are among the most conspicuous large molluscs on Australia’s exposed rocky shores, where they eat algae, and shelter in crevices and under rocks. Still harvested commercially for food, on a small scale.
#860 - Conus sp. - Cone Shell
A fossil cone shell in the rocks at Halls Head - this one has been broken open (hopefully just by erosion) so you can see some of the internal structure.
Cone Shells (family Conidae) are 800 or so species of predatory sea snails, that hunt using specialised radular teeth wielded like poisoned harpoons from the proboscis. And the venom can be very very nasty indeed - a sting from some can kill an adult human in 5 minutes, leading to one common name of ‘cigarette snail’, as in ‘time enough for one last cigarette‘. Since the proboscis is long enough to reach right back to any part of the shell, and the teeth can penetrate wetsuits, the only safe way to pick up a cone shell is to get somebody else to do it.
That said, cone shell venom is medically fascinating - the venom of each cone snail species may contain as many as 200 pharmacologically active components. W-conopeptide, from Conus magus, is the basis of the analgesic drug Prialt, and said to be 1000 times as powerful as morphine and used as a last resort in specific applications. Conopeptides are also being investigated as anti-epileptic agents and to help stop nerve-cell death after a stroke or head injury.
They have some wonderful common names, including Geographer’s Cone, and Astrologer’s Cone. I have no idea what one this is - I’ve only ever seen the one washed up on the beach around here.
#861 - Holopneustes porosissimus - Pored Sea Urchin
A species of distinctively coloured, globe-shaped sea urchins, usually slightly wider than high, and mildly flattened on the ventral side where the mouth is. Adults may be partially pentagonal, and up to 70 mm across.
I don’t know what the species eats, but a related one from the east coast eats sea grass, and there are extensive sea grass beds off the coast here as well.
#862 - Goniastrea australensis - Lesser Star Coral
One of the most common corals around Rottnest Island, just off the coast here, where it forms large masses and encrusting layers. This fossil example was one of many large chunks in the limestone at Halls Head.
It may seem surprising that we even get corals this far south, but we do have the advantage of the Leeuwin Current, a unique warm water current that hugs the coastline here. It’s unique because other western coastlines around the world have cold currents that flow towards the equator- here, warm water that would prefer to flow through the Torres Strait is instead forced to go the long way around Australia - the Leeuwin affects the coastlines as far east as Tasmania. Of course, it also prevents cool, nutrient-rich water from upwelling, and combining that with our lack of rivers leads to an amazingly nutrient-poor shallow water ecosystem along the entire Western coastline. Not that that’s a problem for corals or sea-grasses, who do well without the competition from algae.
#863 - Rhytidoponera sp. - Pony Ant
These are some of the most common ants in Australia but are less so in Melanesia. They can be very abundant in urban areas, with the Green-headed Pony Ant being quite an annoying and aggressive pest. Some species, especially those found in forested areas, forage during the day while many arid zone species forage in the evening and night. They are general predators or scavengers, with some also taking honeydew and others showing a strong preference for seeds. These ones were scavenging along the wrack line on the beach at Halls Head, and carting back their finds - which included a small rove beetle - back to the nest inside a large fossil shell.
Some of the smaller species have a potent sting while others have a weak sting or are entirely unable to sting.
Most pony ant species lack queens and instead have fertilised workers which produce brood. In some, where true queens are present, the queens may be replaced by fertilised workers when they die.
The genus is Panulirus - the family is Palinuridae. That’s because half the genera in the family are anagrams of Palinurus.
The basis of Australia’s most valuable fishery - almost A$250 million back in 2004 - making up 20% of value of Australia’s total fishing economy. The fishery is strictly controlled, which is the main reason that it might actually be sustainable.
I found the empty forequarters of this one on the beach at Halls Head.
#859 - Physalia utriculus - Indo-Pacific Portuguese Man-o-War - Bluebottle
A familiar sight on most Australian beaches, especially after strong winds have blown flotillas of them ashore. The sail on top of the float may be left or righthanded, which is useful since that way any prevailing winds will only blow half the flotilla ashore when they’re sailing down the coast.
Unlike the Portuguese Man-o-War (P. physalis) of the Atlantic, P. utriculus has a single large fishing tentacle, and a smaller float. Physalia are colonial siphonophores, the individual animals specializing into the float, tentacles, gonads and digestive organ, and bound so close together that they can’t survive on their own. The stinging cells, however, can still be potent weeks after they wash ashore.
Advice for swimming when bluebottles are about -Wear protective clothing such as a lycra top, skivvy or stinger suit. This is a good idea anyway, as they’ll protect you from UV burns too.
First Aid
- Do not treat with vinegar - that will just make more nematocysts fire.
- Remove any tentacles from the skin using tweezers or a gloved hand.
- If possible soak for 20 minutes in hot water (42˚C) - the venom is sensitive to heat.
- Apply cold packs, and possibly a pain relieving cream, to the affected area for pain relief. This may need to be repeated for some weeks if the itchiness persists.
Also, try not to inhale any tentacles, should you swim face-first into one.
#858 - Janthina sp. - Purple Bubble-raft Snail
A very unusual snail, often washed up in the same weather that brings Bluebottles ashore. That’s because they share the same habitat - floating around on the surface of the ocean.
Adult Janthina can’t swim - if they lose their grip on the air-filled chitin bubbles they’ll sink to their death in the ocean depths. Until then, they’ll float around eating any suitable prey - the surface-dwelling hydroid colony known as the By-the-wind-Sailor Velella velella is a particular favorite.
Janthina is also counter shaded - the part facing the surface is a darker purple than the side facing down. This is useful counter shading, making them harder to spot by predators above the water and below.
#859 - Turbo sp. - Turban Snail
This is a fossilised Turban Snail, one of many in the incredibly fossil-rich pockets of the limestone outcropping on the beach at Halls Head. The limestone isn’t that old, and by the looks of things all these fossil shells got added to the mix when cavities got eroded in the rock by changing sea levels, filled up with snails and big chunks of coral, became cemented together, and then got exposed again as sea levels dropped once more.
There’s at least two species of Turban Snail living in the waters off Perth today - it’s entirely possible this is one of them.
The Turbinidae originated back in the Permian, 298-250 myo. They’re often large, and have a calcareous operculum to seal the shell entrance when predators threaten. There were a lot of opercula in among the fossils as well.
Species of Turbo are among the most conspicuous large molluscs on Australia’s exposed rocky shores, where they eat algae, and shelter in crevices and under rocks. Still harvested commercially for food, on a small scale.
#860 - Conus sp. - Cone Shell
A fossil cone shell in the rocks at Halls Head - this one has been broken open (hopefully just by erosion) so you can see some of the internal structure.
Cone Shells (family Conidae) are 800 or so species of predatory sea snails, that hunt using specialised radular teeth wielded like poisoned harpoons from the proboscis. And the venom can be very very nasty indeed - a sting from some can kill an adult human in 5 minutes, leading to one common name of ‘cigarette snail’, as in ‘time enough for one last cigarette‘. Since the proboscis is long enough to reach right back to any part of the shell, and the teeth can penetrate wetsuits, the only safe way to pick up a cone shell is to get somebody else to do it.
That said, cone shell venom is medically fascinating - the venom of each cone snail species may contain as many as 200 pharmacologically active components. W-conopeptide, from Conus magus, is the basis of the analgesic drug Prialt, and said to be 1000 times as powerful as morphine and used as a last resort in specific applications. Conopeptides are also being investigated as anti-epileptic agents and to help stop nerve-cell death after a stroke or head injury.
They have some wonderful common names, including Geographer’s Cone, and Astrologer’s Cone. I have no idea what one this is - I’ve only ever seen the one washed up on the beach around here.
#861 - Holopneustes porosissimus - Pored Sea Urchin
A species of distinctively coloured, globe-shaped sea urchins, usually slightly wider than high, and mildly flattened on the ventral side where the mouth is. Adults may be partially pentagonal, and up to 70 mm across.
I don’t know what the species eats, but a related one from the east coast eats sea grass, and there are extensive sea grass beds off the coast here as well.
#862 - Goniastrea australensis - Lesser Star Coral
One of the most common corals around Rottnest Island, just off the coast here, where it forms large masses and encrusting layers. This fossil example was one of many large chunks in the limestone at Halls Head.
It may seem surprising that we even get corals this far south, but we do have the advantage of the Leeuwin Current, a unique warm water current that hugs the coastline here. It’s unique because other western coastlines around the world have cold currents that flow towards the equator- here, warm water that would prefer to flow through the Torres Strait is instead forced to go the long way around Australia - the Leeuwin affects the coastlines as far east as Tasmania. Of course, it also prevents cool, nutrient-rich water from upwelling, and combining that with our lack of rivers leads to an amazingly nutrient-poor shallow water ecosystem along the entire Western coastline. Not that that’s a problem for corals or sea-grasses, who do well without the competition from algae.
#863 - Rhytidoponera sp. - Pony Ant
These are some of the most common ants in Australia but are less so in Melanesia. They can be very abundant in urban areas, with the Green-headed Pony Ant being quite an annoying and aggressive pest. Some species, especially those found in forested areas, forage during the day while many arid zone species forage in the evening and night. They are general predators or scavengers, with some also taking honeydew and others showing a strong preference for seeds. These ones were scavenging along the wrack line on the beach at Halls Head, and carting back their finds - which included a small rove beetle - back to the nest inside a large fossil shell.
Some of the smaller species have a potent sting while others have a weak sting or are entirely unable to sting.
Most pony ant species lack queens and instead have fertilised workers which produce brood. In some, where true queens are present, the queens may be replaced by fertilised workers when they die.