“There are some four million different kinds of animals and plants in the world. Four million different solutions to the problems of staying alive.” David Attenborough

The circle of life on the planet is interconnected with many species and organisms from large animals to small microscopic organisms. While these species and organisms are not in sight every day, they constitute the backbone of our ecosystems giving the earth the biodiversity needed for survival of all life. We, as humans, need to recognize the profound positive multitude of effects these species and organisms provide before more species become extinct, including ourselves. We need to live in a way where we cherish and enhance the abundance these species and organisms freely provide. If we look at the circle of life as links in a chain, when one link is gone, the rest of the chain loses its strength and ability to bind together all that matters for life to exist.

Our oceans sustain almost all of the diversities of phylum in the animal kingdom (Wang, 2013), while animals play an important role in the transport of nutrients both laterally and vertically in our ecosystems on land, in the oceans and in the air (Doughty et al, 2016).

“Potential interlinked system of recycling nutrients. The diagram shows a potential route of nutrient transport of the planet in the past. Red arrows show the estimated fluxes or diffusion capacity of nutrients….Grey animals represent extinct or reduced population densities of animals.” (Credit: Doughty et al, 2016)

While phyla can vary in:

  • size
  • structure, and
  • characteristics

they are integral to marine biodiversity and maintaining marine ecosystems (Wang, 2013).

The cycling of nutrients is accelerated by:

  • animal ingestion,
  • digestion and
  • defecation of plant matter

allowing these nutrients to be reused by other species (Doughty et al, 2016).

However, with the extinction of large numbers of animals, plant matter is decomposing slowly resulting in nutrient poor ecosystems (Doughty et al, 2016).


Whales transport nutrients laterally when moving between foraging and breeding areas and vertically when transporting nutrients to the surface with their fecal plumes and urine (Doughty et al, 2016).

Whales can help:

  • produce
  • contribute
  • transport nutrients to ecosystems faster (Moss, 2017).

Whale strandings transfer marine biomass in the sea-land interface to consumers, such as:

  • bears and other predatory mammals
  • scavenging birds
  • invertebrates, such as flies also improving land ecology (Roman et al, 2014).
Polar Bears (mammals, left), Flies (right)

Increase of whale populations could increase the transfer of nutrients while also helping to regulate carbon levels in the atmosphere into the ocean depths (Doughty et al, 2016).


Large Animals

Large animals play a larger role in the transport of nutrients across sites and even ecosystems of land, sea, rivers, and air (Doughty et al, 2016).

Moose can transfer aquatic biological nitrogen to terrestrial ecosystems, as do bears, otters and eagles, while hippopotamuses can transport nutrients from terrestrial nutrients to aquatic ecosystems (Doughty et al, 2016).

Bears (upper left), Otters (upper right), Hippopotamus (lower left), Eagles (lower right)

Visit the Museum of Natural History in Halifax, Nova Scotia, Canada, to see their mammal exhibit featuring a “life-sized mainland moose, a growling Nova Scotia black bear and a beaver” (Mammals and birds, 2015).

Benthic invertebrates are a source of food for walrus; however, with climate change creating loss of sea ice, walrus must make longer trips to feed since they haul out on ice leaving walrus calves at more risk from predators (Christie et al, 2018).


Domestic animals may assist in nutrient transfer with fenceless pastures and greater diversity of species to increase nutrient abundance and movement (Doughty et al, 2016).

Domestic Animals: Cow (left), Sheep (middle), Horses (right)

While the horses on Sable Island National Park Reserve, a 40 km crescent shaped island “in the North Atlantic Ocean approximately 290 km east-southeast of Halifax, Nova Scotia, Canada” (Tissier et al, 2013), were introduced to the island in the mid 1700’s, they “have always been free-ranging” and constitute “an important part of the ecosystem” (Contasti et al, 2013). The horses also inhabit the island with:

  • 190 plant species,
  • ocean kelp and seaweed that wash ashore,
  • Atlantic Walrus until the 1800’s decimated as a result of being hunted for their tusks,
  • grey seals and harbour seals
  • 350 bird species have been recorded, including both the endangered “Ipswich Sparrow and Roseate Tern”,
  • fish species in ponds,
  • 6 invertebrate species and
  • in the 16th century horses, cattle, goats, and rabbits were released on the island

creating a diverse ecosystem (Parks Canada Agency, & Government of Canada, 2019).

Marine Reptiles

Marine Reptiles

Moss (2017) suggests sea turtles include the:

  • flatback
  • green
  • hawksbill
  • Kemp's ridley
  • leatherback
  • loggerhead
  • olive ridley” turtles

with all but the flatback being listed as “endangered or threatened”.

Just 300 years ago there were 16-33 million sea turtles in the Caribbean; however, their populations have declined to about 10,000 more recently (Moss, 2017).

  • Green sea turtles feed on seagrass to help maintain its productivity and prevent beds from becoming overgrown which can cause an altering of currents, bottom shade, decomposition, habitat for “microorganisms, algae, invertebrates and fungi” (Moss, 2017). The Caribbean has seen a loss in reef fish rich in protein due to loss of green sea turtles (Moss, 2017). Sea turtles promote the growth of vegetation, dependent animals, and reduce sand erosion and upset (Moss, 2017).
  • Loggerhead turtles feed on crustaceans which assist in shell disintegration, create trails on the seafloor as they search out food, assist in nutrients being recycled on the bottom of benthic or ocean ecosystems (Moss, 2017).
  • Leatherback turtles transport nutrients from the Arctic Circle to nutrient exhausted tropical beaches while feeding on jellyfish during their journey (Moss, 2017). While adult sea turtles are prey to killer whales and sharks, a study in Australia suggested 97% of turtle hatchlings get eaten in the water within the 60 minutes of their first swim (Moss, 2017). Sea turtle populations have been reduced from 33-660 million globally to tens to hundreds of thousands today with human hunting also being a factor in their decline for eggs and meat (Moss, 2017).
  • A study of Oliver Ridley turtles suggests they mostly remain in water temperature of 248C to 318C between Gahirmatha and the Sri Lankan coast (Behera et al, 2018).
Iguanas (left), Sea Snakes (right)

Other marine reptiles include iguanas of the Galapagos Islands, sea snakes and saltwater crocodiles of northern Australia, south-east Asia, Indonesia, Malaysia and Indian sub-continent.

Large American crocodile habitat Southern United States and the Caribbean (Moss, 2017).



Seabirds normally:

  • live longer lives
  • breed later in life
  • have fewer young than other birds and
  • often migrate (Moss, 2017).

Seabirds also transport nutrients from the sea to land with seabird islands suggested to be more soil phosphorus rich than non-seabird islands (Doughty et al, 2016).

Both seabirds and whales can redistribute iron nutrients across ecosystems (Doughty et al, 2016).

Unfortunately, larger seabirds, such as the albatross, being the largest seabird, is suggested to be 75% endangered (Doughty et al, 2016) thus slowing the transfer of nutrients from sea to land (Moss, 2017).


Seabirds are the link between the oceans and land in transfer of nutrient concentrations by the transfer of their guano on land, this has decreased with the extinction of seabirds such as the great auk and reduction of condors who were forced to change their diets to land based instead of marine based (Doughty et al, 2016).

Visit the Museum of Natural History, in Halifax, Nova Scotia, Canada, to see their bird exhibit featuring a “live feed from the osprey cam, a life-sized replica of a bald eagle nest and the now extinct passenger pigeon” (Mammals and birds, 2015).

Wooly Monkey

Wooly Monkeys

Studies have also shown that animals can transport significant amounts of nutrients even with no mass flow of their feces from fertile areas to nutrient poor areas (Doughty et al, 2016).

While small animals, such as wooly monkeys, can transport nutrients, larger animals can transport phosphorus outside of their fertile floodplains (Doughty et al, 2016).

Spawning Fish

Anadromous Fish

Anadromous fish that spawn upstream are suggested to have had a larger magnitude of nutrient transfer from the ocean to land than seabirds globally; however, this loss to ecosystems has led to nutrients dropping instead below the photic zone into the great abyss of the oceans instead of transfer to land and also resulting in salmonid loss (Doughty et al, 2016).


Marine Invertebrates

While marine invertebrates are small, they have the largest phyla of marine animals, such as squid now researched for neurobiology and bionics, with oysters being researched in relation to biological evolution and adaptation to stress (Wang, 2013).

Video Link: The Deepest Dive in Antarctica Reveals a Sea Floor Teeming With Life



Due to coral’s sensitivity to changes in their environment, such as ocean acidification and warming ocean waters leading to:

  • loss of stability
  • bleaching
  • coral death

the coral reef is near extinction (Wang, 2013).

Video Link: Coral Reefs 101 | National Geographic

Video Link: A Love Story for the Coral Reef Crisis, by Ayana Elizabeth Johnson, Marine Biologist and Policy Expert


Marine Plants

Marine plants can be separated into two categories: algae and seed plants, with algae being divided into two types: phytoplankton and benthic algae (Wang, 2013).

Phytoplankton is a primary producer in the ocean which fish, shrimp, and shellfish feed on, and is a biological indicator monitoring water quality (Wang, 2013).

When sea water is polluted and/or eutrophic, it will result in reduced or excessive reproduction of phytoplankton, and the latter may lead to a noxious bloom (Wang, 2013).


Benthic algae live at the ocean bottom as “crops on the sea” as green food from the ocean that also has use as:

  • raw material
  • fertilizer
  • marine drugs (Wang, 2013).

Seed plants such as seagrass is rich in humus and is important in the growth for:

  • fish
  • shellfish
  • seabirds (Wang, 2013).

Mangrove plants live in the ocean and are vital in tropical climate regulation and prevention of coastal erosion and growth for:

  • marine animals
  • migratory birds
  • seabirds (Wang, 2013).

Visit the Museum of Natural History, in Halifax, Nova Scotia, Canada, to see their “Rocky Shore: Our Coastal Aquarium” exhibit of marine plants and animals featuring “ odd and wonderful creatures” (Rocky Shore: Our Coastal Aquarium, 2017).

Marine Fungi

Marine Fungi

Nutrition for marine plants and food source for marine protozoans and benthic animals is provided by marine fungi while some marine fungi contribute to:

  • production of antibiotics
  • physiological active substances
  • antitumor activity
  • antibacterial activity, and
  • possibly new drugs (Wang, 2013).

Pseudomonas fungi can degrade pollutants in the marine environment, promoting the self-purification of oceans (Wang, 2013).

Marine Microorganisms

Marine Microorganisms

Marine microorganisms can live deep in the sea in extreme conditions, some of which can be used in

  • oil pollution control
  • antibacterial activity, and
  • antitumor activity (Wang, 2013).
elephants (megaherbivores)

Amazonian Megafauna

The obliteration of our terrestrial megafauna and whales has reduced the ability of other animals to distribute nutrients with estimates in the Amazonian megafauna dropping by up to 50% in the floodplains suggesting this impacts broader global areas of nutrient transfer by wind or water (Doughty et al, 2016).

South America once contained the biggest number of megaherbivores; however, extinctions after the late Pleistocene era reduced this area to ∼1% of its previous capacity to distribute nutrients continent wide also affecting the oceans (Doughty et al, 2016).

To learn more about elephants, go to the following link for information about conservation, interesting facts, and resources, including kid's activities:

Cape Breton, Nova Scotia, Canada (Credit: Maria Lisa Polegatto)

Each of these animals, plants, fungi, and microorganisms is a vital part of our marine ecosystems that we can research through marine biology (Wang, 2013) that connect our marine, air and land ecosystems (Doughty et al, 2016).

“……the ocean gave us infinite power and rich resources, and now it is human's turn to give back to our ocean.” (Wang, 2013).

Continue to next module here:

Created By
Maria Lisa Polegatto


Created with images by Humberto Braojos - "Whales at Moss Landing, California." • Anastasia Taioglou - "Sunrise in Greece" • Joel Henry - "untitled image" • Andres Corredor - "untitled image" • Dan Bolton - "Walking on thin ice" • zulkarnaen ali - "Lalat." • Louis Reed - "A 360 panorama stitched and warped to create the tiny planet effect. Image sequence taken by drone above a community field in Wales." • Kevin Noble - "I had been at Grand Teton National Park for about a week and this was my final morning. I had not had much luck getting a moose shot so decided to pick a spot along Moose-Wilson Road by the ponds and see if anything showed up. Just before the sun rose, a bull and a cow showed up to grab their breakfast. In this shot, the bull headed towards me just as the sun crested lighting up the flowers, grass and his antlers." • Richard Lee - "Alberta wild" • Karl Anderson - "Sea Otter, British Columbia, Canada" • Adolfo Félix - "hippopotamus" • Patrick Brinksma - "Never let your goal out of sight Stay focused Laser focused" • Jay Ruzesky - "untitled image" • Luca Basili - "untitled image" • Sam Carter - "untitled image" • Steve Bittinger - "Ponies near azure sea" • Thibault Carron - "Black and chestnut horses nuzzling" • Michaela - "untitled image" • Tanguy Sauvin - "untitled image" • Serge B - "The moment of truth. Calmly observing iguana. Costa Rica" • Jong Marshes - "untitled image" • Tamar Waskey - "Crocodile in the grass" • Steve Harvey - "Handsome is an “animal ambassador” at the Ojai Raptor Center" • Paul Carroll - "These birds are wonderful parents but this poor chick looked trapped to me." • Martin Jernberg - "When in Kathmandu, we had a fun visit at the monkey temple. Definitely an amazing and unique experience. We rented scooters for only $7 a day and somehow arrived safely to our destination." • Drew Farwell - "www.outdoorjunkiez.com" • Jonathan Diemel - "untitled image" • ali shirali - "Dead Oysters " • David Clode - "The Clown Anemonefish is the type of fish in the film Finding Nemo. This photo shows typical behaviour where they live in and find protection in stinging sea anemones." • Geoffroy Hauwen - "untitled image" • NOAA - "Phytoplankton - the foundation of the oceanic food chain. " • John Mark Arnold - "Underwater Algae" • Maxwell Ridgeway - "The Mangrove" • Sharon McCutcheon - "Colorful orange and green lichen at Dinosaur National Monument near Vernal, Utah" • Michael Longmire - "Closeup of microscope" • Nam Anh - "https://noithatphuongdong.vn/tin-tuc/70/nen-dung-bep-ga-hay-bep-tu---kinh-nghiem-nen-mua-bep-ga-hay-bep-dien-tu" • frank mckenna - "untitled image"