This exhibition is associated with the 11th International Polychaete Conference being held at the Australian Museum in early August 2013.
One of the reasons the Museum is hosting this meeting is that we have two well established polychaete workers at the Museum (Pat Hutchings and Elena Kupriyanova) and one of the largest worm collections in the world. Also many of the participants to the conference will take the opportunity to work on these collections and continue to document the diversity of Australian seaworms.
We selected these images of polychaetes (segmented bristleworms) not only for their beauty, but also because they illustrate the morphological diversity exhibited by these worms. These worms are primarily marine or estuarine. They live from the intertidal to the deepest parts of the ocean. Over 20,000 species have been described and many more remain to be described, especially from Australian waters.
Seaworms range in size from less than a millimetre to several metres in length. They are important in the marine ecosystem as they are found in all levels of the food chain. At the bottom of this food chain are worms which swallow sediment to obtain their nutrients, and are referred to as deposit feeders. Some species spread out their tentacles over the surface of the substrate and hoover up fine particles. The food particles are wrapped up in mucus and these “balls” are moved along in the grooves of the tentacles to the mouth where a series of lips around the mouth roll the food balls into the mouth. Larger sediment particles are used for tube building, whereas smaller ones are swallowed for food. Other worms are herbivores, and some others are suspension feeders – filtering water to obtain organic matter suspended in the water column. Other species are carnivores, catching unsuspecting prey with well developed jaws or muscular throats. Some are even parasitic, and others live in the water column.
Below we illustrate some of these feeding types:
Family Terebellidae: Loimia n. sp. (Photo by Gary Cranitch, specimen from Lizard Island, Great Barrier Reef, photographed alive in the laboratory).
This animal belongs to a yet undescribed and unnamed species and is about 2-3cm in length, currently being described by the Australian Museum research scientist Pat Hutchings. The worm lives in a muddy tube from which it has been taken out of to reveal its structure. Abundant white contractile tentacles are spread out over the surface, and these act like vacuum cleaners, sucking up food particles, a method of provisioning known as surface deposit feeding. This is achieved by the continuous beating motion of fine hairs (or “cilia”) lining the grooves of the tentacles, creating water currents which suck particles of food into the grooves, where they are wrapped in mucus and transported to the mouth.. Larger sediment particles are used in tube construction and the muddy tube needs to be continually maintained. The worm can also “cough” and eject the particles some way away. A common name for these worms is “spaghetti worms” as divers just see the long white tentacles spread out over the substrate which, when touched, rapidly contract back into the sand or under a rock. These tentacles contain chemical compounds which makes them unpalatable to passing fish.
Family Amphinomidae. (Photo by Roger Steene, specimen photographed underwater on the Great Barrier Reef)
These often brightly coloured worms are common in shallow water and on coral reefs and can range in size from a few mm to serveral cm in length. Despite their beauty, these animals are known as ‘fireworms’, because a close encounter with them can result in excruciating pain or worse. Their hollow bristles are loaded with poison produced by glands at the base of each “foot” (or parapodium). While the bristles can easily penetrate even dive gloves, they also break off releasing poison to which some people are highly allergic. Fireworms are slow moving carnivores using their muscular eversible lower lip for rasping on sedentary animals such as sponges, anemones, hydroids and ascidians. These animals are commonly seen cruising around the bottom surface on reefs and have few predators. The taxonomy of this group is still very confused and many of the species have been reported as widespread, but as more detailed molecular and morphological studies are undertaken they are being shown to represent suites of cryptic species, each with very discrete restricted distributions.
Family Acrocirridae: Teuthidodrilus samae Osborn, Madin & Rouse, 2011. (Photo by Michael Awe, specimen from the Celebes Sea, photographed alive in the laboratory aboard the research vessel).
This species known as the “squidworm” was collected deep in the water column of the Celebes Sea (Indonesia) and is about 9cm in length. The animal was initially observed in 2007 with a remotely operated vehicle Max Rover Global Explorer, operated by the Philippines research vessel BRP Hydrographer Presbitera, at depths of 2259-2800 m. Only seven specimens ranging in length from 20-94 mm were collected by the ROV, about 100 m above the seafloor. More individuals were observed on 7 more dives and a total of 16 individuals were seen. How can such a distinctive, large and colourful creature have eluded scientists before? They have been observed swimming very rapidly, and it has been suggested that they can detect the presence of traditional collecting gear perhaps by changes in water movement or pressure and take avoiding action. Underwater film footage indicates that they are suspension feeders that feed on large aggregations of marine “snow” (fine particles of organic matter) found in the water column.
Family Eunicidae: Eunice aphroditois (Pallas, 1788). (Photo by Roger Steene, specimen photographed underwater in the Philippines)
These magnificent iridescent worms have a strong muscular body reaching lengths of 1-2 metres and live in warm, shallow waters. They are ambush predators that patiently wait in a burrow with only their heads sticking out and their five sets of razor-sharp jaws stretched open for an unsuspecting prey. Once they detect a potential prey, they lunge for it in a strike so powerful that can cut a fish in half. It is commonly referred to as the “Bobbitt worm”, as apparently an underwater photographer decided that its hunting methods were similar to the Bobbitt family incident of 1993. The nickname has stuck, despite being inaccurate – Lorena Bobbitt inflicted a grievous injury on her husband’s treasured body part using a knife rather than scissors.
Family Arenicolidae: Arenicola marina (Linnaeus, 1758). (Photo by Alexander Semenov, specimen from the White Sea, photographed alive in the laboratory).
These animals are commonly known as lugworms and live intertidally, burrowing deep in muddy sand sediments and can reach lengths of 6-8cm. At low tide their coiled faecal casts (masses of excrement) may often be seen piled above their burrows. They are “deposit-feeders”, as they feed by constantly indiscriminately swallowing large amounts of sand to obtain nutrients from the bacteria, algae and decaying organic particles found in these sediments. The bushy gills in the middle of the body are red due to the haemoglobin in the blood which helps the worm to survive periods of low oxygen levels during low tide. Lugworms are commonly used by recreational fishers as bait.
Family Phyllodocidae: Phyllodoce citrina Malmgren, 1865. (Photo by Alexander Semenov, specimen from the White Sea, photographed alive in the laboratory)
This animal moves actively over the substrate in a snake-like motion using its bristles and characteristic leaf-like appendages (or “cirri”) as paddles and can reach lengths of 10-12cm. Phyllodocids are carnivorous predators that often hunt on a rising tide by following mucus trails left by a potential prey species. They use their long eversible throat or “pharynx” to catch unsuspecting prey. The eversion of this pharynx is like pulling a sock inside-out, very quickly. Males and females spawn synchronously forming breeding swarms of adults. Females attach bright emerald green mucous capsules containing eggs to stones and algae, into which males have to penetrate to fertilise the eggs. After 3-4 days the capsule breaks down, and microscopic larvae are released and swim into the water column, before settling on the bottom after a few days.
Family Polynoidae: Lepidonotus squamatus (Linnaeus, 1758) (Photo by Alexander Semenov, specimen from the White Sea , photographed alive in the laboratory)
These animals are known as scale worms because they all carry scales (or “elytra”) on their backs, arranged in pairs along the body and can reach lengths of 3-5cm. This species, photographed here under near-fluorescent light using blue filters on strobes and a yellow filter on the lens, has a habit much like the cartoon character “Shrek”, a territorial ogre who lives alone for most of the year, but unlike Shrek, is highly aggressive to any potential intruders. At the time of breeding this habit changes, pairs are formed, mating occurs and the fertilised eggs are released into the water column where the larvae spend some weeks. The adults are carnivores which rapidly evert their pharynx, heavily-armed with teeth, to catch a wide range of unsuspecting prey.
Family Sabellidae: Branchiomma arcticum (Ditlevsen, 1937). (Photo by Alexander Semenov, specimen from the White Sea, photographed alive in the laboratory).
The photographer is looking down into the base of the whorl of feeding tentacles (or “branchial crown”) of this ’fan-worm‘, where the pinkish lips are splayed out in order to direct food particles collected by the filaments to the mouth. The crown is held up into the water column and hairs (“cilia”) along each filament create water current which flows through the filaments, trapping food particles and carrying them to the lips at the base. Small light-sensitive pigmented spots along the branchial crown alert the worm to passing shadows of potential predators and the animal responds rapidly by retracting back into its tube. Like calcareous tube worms, sabellid fan worms can rapidly regenerate their branchial crowns, which are often colourful and are also used for respiration. This rapid regeneration is critical, as, without the crown, the worm can neither feed nor respire. These animals can reach lengths of 5-6cm.
Family Serpulidae: Serpula uschakovi Kupriyanova, 1999. (Photo by Alexander Semenov, specimen photographed underwater in the Sea of Japan).
This flower-like animal described by the Australian Museum research scientist Elena Kupriyanova is a ‘tube worm’ living in a calcareous, chalky tube firmly attached to the substrate and can reach lengths of 1.2cm. This worm uses its colourful branchial crown for both for respiration and feeding. The crown is used to catch tiny food particles, usually algae suspended in the water column, a method of provisioning known as suspension-feeding. One of the branchial filaments is modified into a plug that tightly shuts the tube entrance whenever the worm retracts into it, when alarmed by a passing shadow. If the animal is too slow, its branchial crown can be bitten off, but all is not lost, as it can grow back rapidly.
Family Siboglinidae: Osedax sp. (Photo by Greg Rouse, photographed live in a laboratory aquarium)
These are gutless worms living on the bones of a whale which has found its grave on the seafloor at 633 m in the Monterey Canyon, USA. They are commonly called ‘boneworms’ or ‘zombie worms’. The animals in the photograph are all females which attach to the bones by root-like structures full of friendly symbiotic bacteria that dissolve the bones, thus providing nutrition. Males are too small to be seen because they are no more than tiny bags of sperm hidden inside the female tubes, in harem-like groups, and their only function is to produce sperm. Males also lack symbiotic bacteria and rely solely on females for food in the form of embryonic yolk reserves to fulfil their ’destiny’. In this photograph fertilised eggs are being spawned into the water column. This group of bone-devouring worms was only discovered in 2004 and other species have since been described from many locations world-wide, feeding on bones of marine mammals and large fish.
Family Syllidae: Myrianida pachycera (Augener, 1913). (Photo by Greg Rouse, specimen from Ben Buckler rocks on Bondi Beach, Sydney, photographed live in the laboratory)
The photograph shows a mode of reproduction called “stolonisation”, in which long chains of miniature clones (or “stolons”) are formed, in this species from the tail end of the parent or “stock”. The head of this carnivorous worm is on the bottom left, and midway along the body a series of stolons are forming like linked train carriages, but with new ‘carriages’ being inserted behind the parent ‘locomotive’, not behind the last carriage. The posterior-most stolon is about to break free and swim off, to be followed by the next four individuals. Although often considered a form of asexual reproduction, stoIonisation is intimately connected with sexual reproduction, and is a very efficient way to disseminate gametes quickly - egg and sperm produced by the parent worm are transferred to the stolons which carry them away. The stolons are incapable of regenerating into complete worms that feed independently, but are merely a way for the species to swarm and spawn in great numbers, then die.