Either gills or enhanced lungs/oxygen efficiency. Gills: Permanent operation underwater. In order to be truly effective, you would also need a way to pull water over the gills without moving.

In general, fishes breathe by absorbing dissolved oxygen through their gills; however, in the bathypelagic (or midnight) zone of the ocean, there is zero light, high pressure, low temperature, low nutrients and low dissolved oxygen content. In order to preserve energy, many fishes in this zone have a low metabolism.

Common oceanic animal adaptations include gills, special breathing organs used by some oceanic animals like fish and crabs; blowholes, an opening on the top of the head that’s used for breathing; fins, flat, wing-like structures on a fish that help it move through the water; and streamlined bodies.

• Birds.
• Fishes.
• Reptiles.
• Sea lions.
• Seals.
• Sharks & Rays.
• Squid & Octopuses, etc.
• Whales & Dolphins.

Here are five of the biggest challenges our oceans face, and what we can do to solve them.

1. Climate change. Climate change arguably presents the greatest threat to ocean health.
2. Plastic pollution.
3. Sustainable seafood.
4. Marine protected areas.
5. Fisheries subsidies.

Global warming is causing sea levels to rise, threatening coastal population centers. Many pesticides and nutrients used in agriculture end up in the coastal waters, resulting in oxygen depletion that kills marine plants and shellfish. Factories and industrial plants discharge sewage and other runoff into the oceans.

Overfishing is threatening food security for hundreds of millions of people and destroying ocean ecosystems worldwide. We’ve already removed at least two-thirds of the large fish in the ocean, and one in three fish populations have collapsed since 1950. Put simply, there are too many boats chasing too few fish.

Solutions are as simple as eating the right sort of seafood, to ensuring garbage stays out of our waterways and Oceans.

• Overfishing.
• Irresponsible Fish Farming.
• Ghost Fishing.
• Garbage.
• Acidification.
• Dead Zones.
• Mercury Pollution.
• Offshore Drilling.

The most visible and disturbing impacts of marine plastics are the ingestion, suffocation and entanglement of hundreds of marine species. Marine wildlife such as seabirds, whales, fishes and turtles, mistake plastic waste for prey, and most die of starvation as their stomachs are filled with plastic debris.

Globally, 100,000 marine mammals die every year as a result of plastic pollution. This includes whales, dolphins, porpoises, seals and sea lions. There are two principle ways that encountering marine debris can be fatal for these creatures: ingestion (eating) or entanglement in plastic-based fishing gear.

Deadliest plastics: bags and packaging biggest marine life killers, study finds. Plastic bags and flexible packaging are the deadliest plastic items in the ocean, killing wildlife including whales, dolphins, turtles and seabirds around the globe, according to a review of hundreds of scientific articles.

The Problem: Over 1 million marine animals (including mammals, fish, sharks, turtles, and birds) are killed each year due to plastic debris in the ocean (UNESCO Facts & Figures on Marine Pollution). Currently, it is estimated that there are 100 million tons of plastic in oceans around the world.

How many marine animals die each year from pollution and plastic? 100 million marine animals die each year from plastic waste alone. 100,000 marine animals die from getting entangled in plastic yearly – this is just the creatures we find!

They found that China and Indonesia are the top sources of plastic bottles, bags and other rubbish clogging up global sea lanes. Together, both nations account for more than a third of plastic detritus in global waters, according to a report in The Wall Street Journal.

Studies have found that certain chemicals in plastic can leach out of the plastic and into the food and beverages we eat. Some of these chemicals have been linked to health problems such as metabolic disorders (including obesity) and reduced fertility.

Once in the environment, plastic breaks down into smaller and smaller particles that attract toxic chemicals, are ingested by wildlife on land and in the ocean, and contaminate our food chain. However, plastics are not destroying our environment and compromising our health by themselves.

Plastic bags should be banned. Plastic is non-bio-degradable and thus causes pollution; as it cannot be recycled, burning plastic diffuses harmful smoke. Plastic also emits some radiation. Plastic bags can prove to be a choke hazard for small animals and people.

Plastic affects human health. Toxic chemicals leach out of plastic and are found in the blood and tissue of nearly all of us. Exposure to them is linked to cancers, birth defects, impaired immunity, endocrine disruption and other ailments.

No. There is no good evidence that people can get cancer from using plastics. So, doing things like drinking from plastic bottles or using plastic containers and food bags won’t increase your risk of cancer.

Plastic pollution causes harm to humans, animals and plants through toxic pollutants. It can take hundreds or even thousands of years for plastic to break down so the environmental damage is long-lasting. It affects all organisms in the food chain from tiny species like plankton through to whales.

Plastic bags are difficult and costly to recycle and most end up on landfill sites where they take around 300 years to photodegrade. They break down into tiny toxic particles that contaminate the soil and waterways and enter the food chain when animals accidentally ingest them.