Amazing New 3D Images of Shark Intestines Show They Function Like Nikola Tesla’s Valve
Amazing New 3D Images of Shark Intestines Show They Function Like Nikola Tesla’s Valve
Pacific Spiny Dogfish Spiral Intestine

A CT scan image of the spiral intestine of a Pacific spiny dogfish shark (Squalus suckleyi). The beginning of the intestine is on the left, and the end is on the right. Credit: Samantha Leigh/California State University Dominguez Hills

Contrary to what popular media portrays, we actually don’t know much about what sharks eat. Even less is known about how they digest their food, and the role they play in the larger ocean ecosystem.

For more than a century, researchers have relied on flat sketches of sharks’ digestive systems to discern how they function — and how what they eat and excrete impacts other species in the ocean. Now, researchers have produced a series of high-resolution, 3D scans of intestines from nearly three dozen shark species that will advance the understanding of how sharks eat and digest their food.

Smooth Dogfish

Three smooth dogfish sharks (Mustelus canis). Credit: Elizabeth Roberts/Wikimedia Commons

“It’s high time that some modern technology was used to look at these really amazing spiral intestines of sharks,” said lead author Samantha Leigh, assistant professor at California State University Dominguez Hills. “We developed a new method to digitally scan these tissues and now can look at the soft tissues in such great detail without having to slice into them.”

The research team from California State University Dominguez Hills, the University of Washington, and University of California, Irvine, published its findings July 21 in the journal Proceedings of the Royal Society B.

CT Scan Dogfish Shark Spiral Intestine

A CT scan image of a dogfish shark spiral intestine, shown from the top looking down. Credit: Samantha Leigh/California State University Dominguez Hills

The researchers primarily used a computerized tomography (CT) scanner at the UW’s Friday Harbor Laboratories to create 3D images of shark intestines, which came from specimens preserved at the Natural History Museum of Los Angeles. The machine works like a standard CT scanner used in hospitals: A series of X-ray images is taken from different angles, then combined using computer processing to create three-dimensional images. This allows researchers to see the complexities of a shark intestine without having to dissect or disturb it.

Pacific Spiny Dogfish

A live Pacific spiny dogfish shark (Squalus suckleyi). Credit: Samantha Leigh/California State University Dominguez Hills

“CT scanning is one of the only ways to understand the shape of shark intestines in three dimensions,” said co-author Adam Summers, a professor based at UW Friday Harbor Labs who has led a worldwide effort to scan the skeletons of fishes and other vertebrate animals. “Intestines are so complex — with so many overlapping layers, that dissection destroys the context and connectivity of the tissue. It would be like trying to understand what was reported in a newspaper by taking scissors to a rolled-up copy. The story just won’t hang together.”

Smooth Dogfish Spiral Intestine

A CT scan image of a smooth dogfish shark (Mustelus canis) spiral intestine, shown
from the top looking down. Credit: Samantha Leigh/California State University Dominguez Hills

From their scans, the researchers discovered several new aspects about how shark intestines function. It appears these spiral-shaped organs slow the movement of food and direct it downward through the gut, relying on gravity in addition to peristalsis, the rhythmic contraction of the gut’s smooth muscle. Its function resembles the one-way valve designed by Nikola Tesla more than a century ago that allows fluid to flow in one direction, without backflow or assistance from any moving parts.

This finding could shed new light on how sharks eat and process their food. Most sharks usually go days or even weeks between eating large meals, so they rely on being able to hold food in their system and absorb as many nutrients as possible, Leigh explained. The slowed movement of food through their gut caused by the spiral intestine probably allows sharks to retain their food longer, and they also use less energy processing that food.

This video shows the 3D image of a Pacific spiny dogfish (Squalus suckleyi) spiral intestine. Credit: Samantha Leigh/California State University Dominguez Hills

Because sharks are top predators in the ocean and also eat a lot of different things — invertebrates, fish, mammals and even seagrass — they naturally control the biodiversity of many species, the researchers said. Knowing how sharks process what they eat, and how they excrete waste, is important for understanding the larger ecosystem.

“The vast majority of shark species, and the majority of their physiology, are completely unknown. Every single natural history observation, internal visualization and anatomical investigation shows us things we could not have guessed at,” Summers said. “We need to look harder at sharks and, in particular, we need to look harder at parts other than the jaws, and the species that don’t interact with people.”

This video shows the soft tissue of a Pacific spiny dogfish (Squalus suckleyi) spiral intestine, rotated and viewed from different angles. Credit: Samantha Leigh/California State University Dominguez Hills

The authors plan to use a 3D printer to create models of several different shark intestines to test how materials move through the structures in real time. They also hope to collaborate with engineers to use shark intestines as inspiration for industrial applications such as wastewater treatment or filtering microplastics out of the water column.

Reference: 20 July 2021, Proceedings of the Royal Society B.
DOI: 10.1098/rspb.2021.1359

Other co-authors on the paper are Donovan German of University of California, Irvine, and Sarah Hoffmann of Applied Biological Services.

This research was funded by Friday Harbor Laboratories, the UC Irvine OCEANS Graduate Research Fellowship, the Newkirk Center Graduate Research Fellowship, the National Science Foundation Graduate Research Fellowship Program and UC Irvine.

WTO takes important steps towards global trade rules for sustainable fishing
WTO takes important steps towards global trade rules for sustainable fishing
The EU and the WTO | Brussels, 15 July 2021

On 15 July, the World Trade Organization (WTO) held a ministerial meeting on fisheries subsidies, which confirmed the commitment to set the course for a successful outcome on negotiations before the WTO’s Ministerial Conference starting in November 2021.

The Ministers reconfirmed their shared objective to reach an agreement that will make a meaningful contribution to halting the continued degradation of the world’s fisheries resources and the economic activities, and livelihoods they support. While some divergences remain, the consolidated text proposed by the Chair of the negotiations provides a solid basis for the final leg of the negotiations.

In his remarks to his counterparts across the world, Executive Vice-President and Commissioner for Trade Valdis Dombrovskis said: “Protecting global fisheries resources is a shared responsibility and, as such, achieving a multilateral outcome is the only way to address the issue of harmful subsidies. We welcome Director-General Okonjo-Iweala’s commitment to reaching an agreement ahead of the 12th Ministerial Conference and we are fully committed to this objective. The mandate laid out in UN Sustainable Development Goal 14.6 must remain our guide in these negotiations.”

The European Union (EU), in its Common Fisheries Policy, has long prioritised an approach that ensures that fishing is environmentally, economically and socially sustainable. This has been the result of a deep reform process, phasing out harmful subsidies in favour of positive subsidies that promote sustainable fishing and strengthening systems to manage fishing activities. Based on this positive experience, the EU also advocates that WTO rules must be based on sustainability.

Read the statement of Executive Vice-President and Commissioner for Trade Valdis Dombrovskis

Fishing rules: Compulsory CCTV for certain vessels to counter infractions
Fishing rules: Compulsory CCTV for certain vessels to counter infractions
  • On-board cameras (CCTV) to be compulsory for vessels that are likely to not comply
  • Recreational fishermen who do not respect EU conservation measures or fisheries rules should be penalised
  • New measures to address loss of fishing gear
  • Fish should be traced throughout the whole food chain, including processed and imported products

Parliament adopted today its negotiating position on the new Fisheries Control system, which will reform the rules that have governed EU fishing activities since 2010.

By 401 votes in favour, 247 against and 47 abstentions, MEPs agreed to use new technologies to better enforce fishing rules and improve security and transparency. They also insist that consumers must know when, where and how the products they buy are caught.

The use of on-board cameras (CCTV) to carry out checks on landing obligations should be compulsory for a “minimum percentage” of vessels longer than 12 meters and which have been identified as “posing a serious risk of non-compliance”. The equipment will also be imposed as an accompanying sanction for all vessels that commit two or more serious infringements. Vessels that are willing to adopt CCTV on a voluntary basis should be offered incentives such as additional allocation of quotas or having their infringement points removed.

MEPs back the proposal to harmonise sanctions and demand that a “European Union Register” of infringements be set up to centralise information from all member states. They also call for an “appropriate system of sanctions” for infringements committed by recreational fishermen.

Reduce waste, increase security and transparency

In line with the EU’s Farm-to-Fork Strategy, Parliament demands that the origin of fishery and aquaculture products must be traceable throughout the whole food chain, including processed and imported products. Data on the species of fish, the location, date and time it was caught, and the type of gear used should be made available.

In an effort to reduce marine litter, MEPs agree that all vessels should be obliged to notify national authorities when they lose fishing gear and to carry on board the necessary equipment to retrieve it.

All vessels should also be equipped with a geolocation device allowing them to be automatically located and identified, a measure deemed necessary to improve security at sea, according to the adopted text.

Parliament also proposes to increase the margin of error accepted on the weight of some species estimated by fishermen on board (margin of tolerance).

Quote

Clara AGUILERA (S&D, ES), rapporteur, stated: “We took important steps towards having common rules. Inspections on fisheries in Spain must not differ from those in Denmark, Poland or Italy. They must be harmonised and more efficient, without resulting in more red tape for the sector.”

Next Steps

With today’s vote, Parliament is now ready to start negotiations with Council. According to the current proposal, operators would have four years following the entry into force of the rules to equip vessels with the new technologies required.

Background

On 5 February, the Committee on Fisheries adopted its position regarding the EU’s Fisheries Control system. The proposal updates five existing regulations and harmonise control and inspection systems, as well as sanctions, across EU countries.

6.1 billion EUR for sustainable fisheries and safeguarding fishing communities | News | European Parliament
6.1 billion EUR for sustainable fisheries and safeguarding fishing communities | News | European Parliament

, https://www.europarl.europa.eu/news/en/press-room/20201126IPR92519/

  • Funding must not result in an increase in fishing capacity
  • Tailored support for small-scale coastal fishing, young fishermen and outermost regions
  • Fighting illegal, unreported and unregulated fishing

On Friday, EU legislators reached a provisional agreement on how EU countries will be able to spend funds allocated to fisheries and aquaculture for 2021-2027.

The European Maritime, Fisheries and Aquaculture Fund (EMFAF) for the period 2021-2027 amounts to 6.1 billion EUR (6.108 billion EUR in current prices). 5.3 billion EUR will be allocated for the management of fisheries, aquaculture and fishing fleets, while the remaining sum will cover measures such as scientific advice, controls and checks, market intelligence, maritime surveillance and security.

Member states will have to spend at least 15% of the money on efficient fisheries control and enforcement, including fighting against illegal, unreported and unregulated fishing. In line with the Green Deal, actions under the fund will contribute to the overall budget objective to dedicate 30% of funds to climate action.

Compensation for fishermen

If fishermen’s activities cease permanently, they can be supported to scrap or decommission a vessel. In order to receive compensation, the equivalent fishing capacity is permanently removed from the EU fishing fleet register and the beneficiary must not register any fishing vessel within five years of receiving support.

If fishing activities cease temporarily, fishermen may be granted compensation for a maximum duration of 12 months per vessel or per fisherman during the programming period.

Specific needs of small-scale coastal fishing and young fishermen

Member states will need to take into account the specific needs of small-scale coastal fishing, including simplifying administrative requirements. Also, first acquisition of a fishing vessel or partial ownership (of at least 33%) can be funded if the fisherman is no more than 40 years of age and has worked for at least five years as a fisherman or has acquired the equivalent qualification. Fishermen can purchase small-scale coastal vessels (total length less than 12 meters) that have been registered for three years or vessels up to 24 meters that have been registered for five years.

Small-scale vessels may also receive support to replace or modernise engines if the new or modernised engine does not have more power in kW than that of their current engine.

Improving safety, working conditions and energy efficiency

A fishing vessel that is not longer than 24 meters and older than 10 years can have its gross tonnage increased if this results in significant improvements, such as renovating accommodation and other facilities for the well-being of the crew, better on-board fire prevention and safety systems, increased energy efficiency or lower CO2 emissions.

Other key measures

– Engines can be replaced or modernised under strict conditions: for vessels between 12 and 24 meters and at least five years old, the new or modernised engine must not have more power in kW and a reduction of 20% CO2 emissions must be ensured; the fishing capacity withdrawn due to engine replacement or modernisation cannot be replaced.

– Focus on outermost regions: member states will have to prepare an action plan for each of their outermost regions; specific budget allocations are foreseen.

– Support may also be granted for storage of fisheries products in exceptional events generating a significant disruption of markets.

Quote

Rapporteur Gabriel Mato (EPP, ES) said: “We reached a balanced agreement on the future European Maritime, Fisheries and Aquaculture Fund. A fund that would enable the EU fleet to fish and farm better, not to fish more. A fund that would allow the sector to invest in workers’ safety and wellbeing and environmentally-efficient engines and vessels. And a fund that would allow for generational renewal, while avoiding overcapacity and overfishing. The fishing and aquaculture sectors and the whole seafood value chain need support now more than ever to face current and future challenges.”

Next steps

Parliament and Council are now expected to endorse the agreement. The provisions of the regulation will then apply as of 1 January 2021.

Background

The European Maritime and Fisheries Fund proposal was published by the Commission in June 2018 and refers to the Multiannual Financial Framework for 2021-2027. The previous EMFF budget covering the years 2014 to 2020 amounted to 6.4 billion EUR.