What baby crown-of-thorns starfish eat


This 2016 video from Australia is about crown-of-thorns starfish.

From the University of Sydney in Australia:

Eating habits of baby predator starfish revealed

Juvenile crown-of-thorns starfish will eat almost anything to survive, complicating plans for their management

July 21, 2020

The varied diet of juvenile crown-of-thorns starfish complicates scientists’ ability to age them. This makes plans for the management of this invasive species more difficult, as outbreaks of adults on the reef are unpredictable.

Adult crown-of-thorns starfish pose one of the greatest threats to the Great Barrier Reef due to their coral diet. Marine life, including fish, crabs, seahorses, and turtles, depend on coral as a food source, as well as for shelter. No coral means no smaller creatures. This has a domino effect, ultimately decimating the food chain and ecosystem. Learning more about this starfish is crucial for efforts to save the Reef.

New research from Dione Deaker, a PhD student at the University of Sydney, and her adviser Professor Maria Byrne, along with colleagues at the National Marine Science Centre, Coffs Harbour, adds another piece to the crown-of-thorns puzzle. The research team has already shown that baby starfish can survive on algae for up to six and a half years instead of switching to a coral diet at four months of age, per their typical growth pattern. Now, they have discovered that juveniles can eat a range of algae, not just the algae they are thought to prefer; crustose coralline algae. They can even subsist on biofilm — microorganisms that cover the sea floor, including bacteria and protists — to avoid starvation.

“The diet flexibility of juvenile crown-of-thorns starfish complicates our ability to age this species and, therefore, our ability to predict devastating outbreaks of adults on reefs,” Ms Deaker said.

“There is potential for reserves of juveniles to accumulate on the reef and produce outbreaks when favourable feeding conditions arise.

“There is no doubt that these starfish are extremely opportunistic and resilient when their preferred food source is limited. We now demonstrate that this resilience also applies to the youngest juveniles.”

The researchers came to their conclusions, published in influential journal PLOS ONE, after feeding newly settled juveniles either crustose coralline algae, a different kind of algae (Amphiroa) or biofilm in a controlled environment, and then monitoring their growth.

Small juvenile crown-of-thorns starfish are just millimetres in diameter. Once they switch to a coral diet, they can grow to up to a metre wide.

Which fish eat crown-of-thorns starfish?


This August 2016 video says about itself:

Crown of thorns starfish are responsible for more than half of all coral loss on the Great Barrier Reef. Scientists are looking for ways to use their natural enemy, the giant triton, to disperse the starfish – including using the triton’s scent.

From the Australian Institute of Marine Science:

Fish feces reveals which species eat crown-of-thorns

Great Barrier Reef research finds the destructive starfish is eaten more often than thought

May 18, 2020

Crown-of-thorns starfish are on the menu for many more fish species than previously suspected, an investigation using fish poo and gut goo reveals.

The finding suggests that some fish, including popular eating and aquarium species, might have a role to play in keeping the destructive pest population under control.

The native starfish (Acanthaster solaris) is responsible for widespread damage to the Great Barrier Reef. Since 1962 its population has surged to plague proportions on three occasions, each time causing the loss of large amounts of hard coral. A fourth outbreak is currently underway.

Increasing the amount of predation on starfish has long been touted as a potential solution to preventing outbreaks. However, aside from a mollusc called the Giant Triton (Charonia tritonis), identifying what eats it has been a challenging task.

Now, a team of scientists led by Dr Frederieke Kroon from the Australian Institute of Marine Science in Townsville, Australia, has applied a genetic marker unique for crown-of-thorns, developed at AIMS, to detect the presence of starfish DNA in fish poo and gut contents.

Over three years, Dr Kroon’s team used it on samples taken from 678 fish from 101 species, comprising 21 families, gathered from reefs experiencing varying levels of starfish outbreak.

“Our results strongly indicate that direct fish predation on crown-of-thorns may well be more common than is currently appreciated,” said Dr Kroon.

The study, published in the journal Scientific Reports, confirms that at least 18 coral reef fish species — including Spangled Emperor (Lethrinus nebulosus), Redthroat Emperor (Lethrinus miniatus) and Blackspotted Puffer (Arothron nigropunctatus) — consume young or adult starfish on the reef.

Among the species were nine which had not been previously reported to feed on crown-of-thorns. These include the Neon Damsel (Pomacentrus coelistis), Redspot Emperor (Lethrinus lentjan), and the Blackspot Snapper (Lutjanus fulviflamma).

“Our findings might also solve a mystery — why reef areas that are closed to commercial and recreational fishing tend to have fewer starfish than areas where fishing is allowed,” said Dr Kroon.

She and colleagues from AIMS worked with researchers from CSIRO Land and Water and managers from the Great Barrier Reef Marine Park Authority to conduct the study.

“This innovative research sheds new light on the extent that coral reef fishes eat crown-of-thorns starfish,” said Mr Darren Cameron, co-author of the paper, and Director of the COTS Control Program at the Great Barrier Reef Marine Park Authority.

“A number of the fish species shown to feed on these starfish are caught by commercial and recreational fisheries, highlighting the importance of marine park zoning and effective fisheries management in controlling crown-of-thorns starfish across the Great Barrier Reef.”

Brittle stars see with their skin


This 6 May 2020 video says about itself:

Brittle Stars Could Teach Robots To See With Their Skin

Brittle stars are eyeless, brainless animals that spend their time hanging out in dark crevices of coral reefs. But despite all this, it seems that they can still see…using their skin!

Hosted by: Hank Green.

Unusual deep-sea sea cucumbers


This 12 March 2020 video says about itself:

The sea pig Scotoplanes is one of the most abundant animals found on the abyssal plain. These unusual sea cucumbers walk around the seafloor on elongated tube feet which keep them from sinking into the soft mud. They are deposit feeders, digging decaying pieces of algae and animals out of the mud using ten tentacles surrounding their mouth. Long, whip-like sensory organs, called papillae, help them find nutrient-rich food falling down from shallower waters. Their populations are directly influenced by what is happening at the surface of the ocean. For example, large groups of sea pigs can be found feasting near sunken whale carcasses and other food falls on the seafloor.

In 2016, MBARI documented a surprising relationship between sea pigs and king crabs (Neolithodes diomedeae). During a survey of an open area of muddy seafloor, 96 percent of the juvenile crabs were observed clinging to the undersides of Scotoplanes sea cucumbers, presumably for protection from predators. We don’t yet know how the hosts may be benefiting from their little hitchhikers. Our researchers are still digging up new facts about the sea pig.

Common name: Sea pig
Scientific name: Scotoplanes
Reported depth range: 1,000 meters – 6,000+ meters (3,300 – 19,500+ feet)
Size: to 17 centimeters (6.5 inches)

Editor: Ted Blanco
Writer: Kyra Schlining
Production team: Kyra Schlining, Susan von Thun, Nancy Jacobsen Stout

Feather stars and sea lilies, video


This 13 December 2019 video says about itself:

Crinoids, with their elegant, flower-like appearance, are commonly known as feather stars and sea lilies. MBARI remotely operated vehicles have observed several crinoid species from shallow to deep areas on the seafloor from the Aleutian Islands off Alaska to Baja California, Mexico. Their feathery arms capture small plankton, drifting in the currents. The food is then moved to the mouth, which faces up in the center of the arms. Sea lilies are always attached with a holdfast and cannot move. However, feather stars can swim away at the slightest disturbance.

Swiming sea cucumbers, video


This 14 June 2019 video says about itself:

Weird and Wonderful: Swimming sea cucumbers

It can be hard to move from place to place for many animals that live on the seafloor and move slowly. Most sea cucumbers (Holothurians) live a sedentary life on the bottom of the ocean, eating sediment or detritus that rains down from above. But some sea cucumbers leave the life of eating and pooping on the seafloor temporarily by swimming. They may do this as a defense behavior, or to find a mate. Sea cucumbers have made remarkable adaptations to master the challenges of living in the deep sea.

For more information on the importance of holothurians in deep ecosystems see here.

Cambrian age sea star ancestor discovery


This June 2018 video is called The Evolution of Echinoderms.

From Ohio State University in the USA:

Scientists discover evolutionary link to modern-day sea echinoderms

Research team solves fossil mystery, identifies new species

May 2, 2019

Scientists at The Ohio State University have discovered a new species that lived more than 500 million years ago — a form of ancient echinoderm that was ancestral to modern-day groups such as sea cucumbers, sea urchins, sea stars, brittle stars and crinoids. The fossil shows a crucial evolutionary step by echinoderms that parallels the most important ecological change to have taken place in marine sediments.

The discovery, nearly 30 years in the making, was published recently in the Bulletin of Geosciences and provides a clue as to how creatures were able to make the evolutionary leap from living stuck to marine sediment grains — which were held together by gooey algae-like colonies, the original way that echinoderms lived — to living attached to hard, shelly surfaces, which is the way their modern-day descendants live now on the bottom of the ocean.

“It throws light on a critical time, not just in the evolution of organisms, but also in the evolution of marine ecosystems,” said Loren Babcock, co-author of the study and professor of earth sciences at Ohio State. “This represents a creature that clearly was making the leap from the old style of marine ecosystems in which sediments were stabilized by cyanobacterial mats, to what ultimately became the present system, with more fluidized sediment surfaces.”

The creature, a species of edrioasteroid echinoderm that Babcock and his researchers named Totiglobus spencensis, lived in the Cambrian Period — about 507 million years ago. (The Earth, for the record, is about 4.5 billion years old.) A family of fossil hunters discovered the fossil in shale of Spence Gulch, in the eastern part of Idaho, in 1992, and donated it to Richard Robison, a researcher at the University of Kansas and Babcock’s doctoral adviser. That part of the country is rich with fossils from the Cambrian period, Babcock said.

For years, the fossil puzzled both Babcock and Robison. But the mystery was solved a few years ago, when Robison’s fossil collection passed to Babcock after Robison’s retirement.

Once Babcock had the fossil in his lab, he and a visiting doctoral student, Rongqin Wen, removed layers of rock, exposing a small, rust-colored circle with numerous tiny plates and distinct arm-like structures, called ambulcra. Further study showed them that the animal attached itself to a small, conical shell of a mysterious, now-extinct animal called a hyolith using a basal disk — a short, funnel-like structure composed of numerous small calcite plates.

The discovery was a type of scientific poetry — years earlier, Babcock and Robison discovered the type of shell that this animal appeared to be attached to, and named it Haplophrentis reesei.

The edrioasteroid that Babcock and Wen discovered apparently lived attached to the upper side of the elongate-triangular hyolith shell, even as the hyolith was alive. They think a sudden storm buried the animals in a thick layer of mud, preserving them in their original ecological condition.

Echinoderms and hyoliths first appeared during the Cambrian Period, a time in Earth’s history when life exploded and the world became more biodiverse than it had ever been before. The earliest echinoderms, including the earliest edrioasteroids, lived by sticking to cyanobacterial mats — thick, algae-like substances that covered the Earth’s waters. And until the time of Totiglobus spencensis, echinoderms had not yet figured out how to attach to a hard surface.

“In all of Earth’s history, the Cambrian is probably the most important in the evolution of both animals and marine ecosystems, because this was a time when a more modern style of ecosystem was first starting to take hold,” Babcock said. “This genus of the species we discovered shows the evolutionary transition from being a ‘mat-sticker’ to the more advanced condition of attaching to a shelly substrate, which became a successful model for later species, including some that live today.”

In the early part of the Cambrian Period — which started about 538 million years ago — echinoderms likely lived on that algae-like substance in shallow seas that covered many areas of the planet. The algae, Babcock said, probably was not unlike the cyanobacterial mats that appear in certain lakes, including Lake Erie, each summer. But at some point, those algae-like substances became appealing food for other creatures, including prehistoric snails. During the Cambrian, as the population of snails and other herbivores exploded, the algae-like cyanobacterial mats began to disappear from shallow seas, and sediments became too physically unstable to support the animals — including echinoderms — that had come to rely on them.

Once their algae-like homes became food for other animals, Babcock said, echinoderms either had to find new places to live or perish.

Paleontologists knew that the creatures had somehow managed to survive, but until the Ohio State researchers’ discovery, they hadn’t seen much evidence that an echinoderm that lived this long ago had made the move from living stuck to cyanobacterial-covered sediment to living attached to hard surfaces.

“This evolutionary choice — to move from mat-sticker to hard shelly substrate — ultimately is responsible for giving rise to attached animals such as crinoids,” Babcock said. “This new species represents the link between the old lifestyle and the new lifestyle that became successful for this echinoderm lineage.”

Sea cucumber fossil relative discovery


This 11 April 2019 video shows a 3D reconstruction of Sollasina cthulhu. Tube feet are shown in different colors. Credit: Imran Rahman, Oxford University Museum of Natural History.

From the University of Oxford in England:

Cthulhu‘ fossil reconstruction reveals monstrous relative of modern sea cucumbers

New species of extinct sea cucumber named Sollasina cthulhu, for its resemblance to H.P. Lovecraft’s famous monster

An exceptionally-preserved fossil from Herefordshire in the UK has given new insights into the early evolution of sea cucumbers, the group that includes the sea pig and its relatives, according to a new article published today in the journal Proceedings of the Royal Society B.

Palaeontologists from the UK and USA created an accurate 3D computer reconstruction of the 430 million-year-old fossil which allowed them to identify it as a species new to science. They named the animal Sollasina cthulhu due to its resemblance to monsters from the fictional Cthulhu universe created by author H.P. Lovecraft.

Although the fossil is just 3 cm wide, its many long tentacles would have made it appear quite monstrous to other small sea creatures alive at the time. It is thought that these tentacles, or ‘tube feet’, were used to capture food and crawl over the seafloor.

Like other fossils from Herefordshire, Sollasina cthulhu was studied using a method that involved grinding it away, layer-by-layer, with a photograph taken at each stage. This produced hundreds of slice images, which were digitally reconstructed as a ‘virtual fossil’.

This 3D reconstruction allowed palaeontologists to visualise an internal ring, which they interpreted as part of the water vascular system — the system of fluid-filled canals used for feeding and movement in living sea cucumbers and their relatives.

Lead author, Dr Imran Rahman, Deputy Head of Research at Oxford University Museum of Natural History said:

“Sollasina belongs to an extinct group called the ophiocistioids, and this new material provides the first information on the group’s internal structures. This includes an inner ring-like form that has never been described in the group before. We interpret this as the first evidence of the soft parts of the water vascular system in ophiocistioids.”

The new fossil was incorporated into a computerized analysis of the evolutionary relationships of fossil sea cucumbers and sea urchins. The results showed that Sollasina and its relatives are most closely related to sea cucumbers, rather than sea urchins, shedding new light on the evolutionary history of the group.

Co-author Dr Jeffrey Thompson, Royal Society Newton International Fellow at University College London, said:

“We carried out a number of analyses to work out whether Sollasina was more closely related to sea cucumbers or sea urchins. To our surprise, the results suggest it was an ancient sea cucumber. This helps us understand the changes that occurred during the early evolution of the group, which ultimately gave rise to the slug-like forms we see today.”

The fossil was described by an international team of researchers from Oxford University Museum of Natural History, University of Southern California, Yale University, University of Leicester, and Imperial College London. It represents one of many important finds recovered from the Herefordshire fossil site in the UK, which is famous for preserving both the soft as well as the hard parts of fossils.

The fossil slices and 3D reconstruction are housed at Oxford University Museum of Natural History.