Marine Bio - Non-Guest Lectures

How much of the planet does the deep ocean cover?

60%

What level of diversity does the ocean have?

High (the most) diverse ecosystem

Why is the deep ocean difficult to study?

The immense air pressure

What do we know more about than the deep ocean?

Surface of the moon

What percent of the ocean is unknown?

20%

Compared to deeper depths, what has a lot of data?

Shallow depths

How do we study the deep sea?

Remote sampling

What is remote sampling?

Collecting data using machinery/tools

What is a popular deep-sea submersible used for remote sampling?

ALVIN

What’s the sampling pattern with deep sea diversity?

Large amount of sampling, small amount of deep-sea species discovered

What is the CoML (census) for deep-sea diversity?

There is high diversity and low abundance (a lot of different species)

What happens to the “rare is common” pattern as depth increases?

The pattern increases (exaggerates)

What are most pelagic species in terms of feeding style?

Predators

In terms of mesopelagic adaptations, why do they have large/specialized eyes?

Occur due to low light to help them see prey

What are photophores?

Specialized organs that emit bioluminescent light

In terms of mesopelagic adaptations, what are photophores used for?

Predator avoidance (confusing them) and communication with other organisms

In terms of mesopelagic adaptations, what is buoyancy compensation?

Having specialized tissue or a gas bladder that enables organisms to float without swimming 24/7

In terms of mesopelagic adaptations, what does low O2 compensation include?

Large gills and slow metabolism (use oxygen slow and efficiently)

What is the copepods species name?

Gaussia princeps

Where can Gaussia princeps be found?

Deep (>1000m) or shallow waters (25-50m)

How does Gaussia princeps use bioluminescence?

Startle or shoot at predators

What are jellyfish species found in the deep sea?

Aglantha

What stage is Aglantha in?

Hydromedusa, medusa stage (vs polyps)

What are the colours you see in Aglantha jellyfish?

Diffraction of light, not bioluminescence

What ctenophores are common in the deep sea?

Comb jellies

How many combs/rows of cilia do comb jellies have?

Eight

Do comb jellies have bioluminescence?

No, but they diffract light to have a “rainbow-like” colour

What does comb jellies’ red colour help with?

Hide the prey in their stomach

What do photophores help deep sea octopus do?

Hide their silhouettes from predators

What does the red colour of octopus do at great depths?

Looks black so hides them from predators

What is a famous deep-sea octopus?

Dumbo Octopus, known for its huge ears and lethargic state

What is freediving?

The sport of diving underwater with only a singular breathe

Who holds the record in freediving and at what depth?

Hebert Nitcsh, depth of 153m (equivalent to a skyscraper)

Why does the deep sea have little food?

Distance from the shore, decomposition, low primary production over the deep sea bottoms

What is marine snow?

Constant shower of organic material

Why is marine snow important for deep-sea organisms?

Main source of nutrients (food)

What is the sinking rate of marine now?

92m per day

How long does it take marine snow to reach 4000m?

43 days

What percent of surface food reaches open ocean abyssal bottoms?

Less than 0.25%

What percent of surface food reaches the open sea?

0.3-1.5%

What percent of surface food reaches the continental shelf?

2-2.5%

What key factors differs the benthic from the pelagic community?

The presence of a bottom

Once food reaches the bottom of the ocean, what happens?

It remain there and can be utilized

What is the basic deep-sea community pathway?

Detritus → meiofauna → macrobenthos

Compared to continental shelf depths, deep sea oxygen consumption is…?

100x less

Compared to the continental shelf bottoms, deep sea carbon use is..?

Only 2% of what continental shelf bottoms carbon use is

Why is deep-sea biomass so low?

Low muscle mass and efficient predators

What depths are deep-water coral mounds found at?

Greater than 1000m

What do deep-water coral mounds form on top of?

Glacial rock deposits

What type of coral are deep-water coral mounds dominated by?

Calcareous corals

Do deep-water coral mounds have zooxanthellae?

No

What threatens deep-water coral mounds?

Deep-sea trawlers

What are deep-sea trawlers?

Large fishing boats (vessels)

What benthic fauna is the deep-sea dominated by (name 3)?

Deposit-feeding worms, echinoderms, crustaceans

Are the deposit-feeding worms, echinoderms, and crustcaeans deposit feeders?

Yes (eat organic material in sediments)

What happens to deposit feeders after, in terms of a food web?

Eaten by predators

What are the two main kinds of sea cucumbers?

Sea pigs and swimming sea cucumbers

When did crinoids appear?

425 MYA, paleozoic era

What are sea lilies?

Mobile echinoderms, deep-sea crinoids

What do “falls” refer to in baitfalls/whalefalls?

Sinking of a dead organism

Why are baitfalls/whalefalls important to the benthos?

Important source of food to benthos, can take years to consume

How does organism mass affect “falls” as a food source?

The more mass, the more energy available, the longer it takes to consume

What is the key difference between blue whales and narwhals?

Their weight: narwhals = 940kg, blue whales = 140,000kg

What is concentric diversity?

Concentration of species in rings

Why do rings form at vents?

The central heat dissipates quickly, species find their optimal temperature to live at

Where does concentric diversity also happen?

Cold seeps

Cold seeps “rings” are formed due to what?

Carbonate, sulphide concentration, gas hydrates

What is dispersal?

Organisms migrating away from where they were born

Can dispersal occur quickly or slowly?

Both

What are cetaceans?

Air-breathing, aquatic mammals

What are the two subgroups of cetceans?

Mysticati and odontoceti

What are the main traits of odontoceti?

Singular blow hole, echolocates (through the melon), eat using teeth, deep divers

What are the main traits of mysticati?

Double blow hole, eat using baleen, shallow divers, do not echolocate

What are cetaceans most closely related to?

Even-toed ungulates (artiodactyls), specifically hippo

What group are baleen whales apart of?

Mysticati

How do baleen whales generally migrate?

Large migrations following biomass increases of prey

Which group are dolphins and porpoises apart of?

Odontoceti

What are the differences in teeth and vocal range between dolphins and porpoises?

Dolphins have sharp and long teeth and vocalize in a human range, porpoises have dull and short teeth and vocalize in a higher range

Where do narwhals live?

Arctic coastal waters

What is the average group size for narwhals?

15-20

Narwhals’ tusk are a modification of what?

Left canine tooth

What about the rest of narwhals’ teeth?

Vestigial = useless

What is the tusk length of walruses?

Up to 1m

What is the special sensory structure of walruses?

Whiskers (vibrissae) detect clams and prey

What is walruses’ blubber thickness and purpose?

up to 15cm, conserve energy and insulate

How do walruses gather socially?

Hundreds to thousands

What is the diving ability of walruses?

Dive up to 90m, hold their breath for 30 minutes

What is the diet of walruses?

Primarily clams, other benthic invertebrates

What do walruses rely on ice for?

Breeding and rest

What is the difference in body shapes between dolphins and porpoises?

Dolphins have longer bodies, sharper fin, and longer beaks. Porpoises have shorter bodies, shorter beak, and dorsal fin

52 MYA, what species were discovered and where?

Pakicetus, discovered in the Tethys Sea (Pakistan)

49 MYA, what species were discovered and what was their key movement?

Ambulocetus natans, hind legs resembled whale fluke (tails) & backbone moved up and down

40 MYA, what species was discovered and what does it represent?

Basilosaurus (Tethys Sea), first fully aquatic whale ancestor.

What happened to nostrils of the ancestors of whales?

Migrated backwards to form what is now the modern blowhole

What discovery was made in 2001 regarding whale evolution?

Linking whales to ungulates

What discovery was made in 2006 about baleen whales?

In Australia, baleen whales from 25 MYA used to have teeth instead of baleens

What discovery was made in Antarctica in 2011?

Basilosaurus

What is countershading and when is it used?

In the Deep Ocean: camouflage pattern where an animal is darker on top and lighter on the bottom

How do anglerfish use bioluminescence in the deep sea?

For hunting and mating, a glowing esca attracts prey (the light can help find mates)

What is an esca?

A bioluminescent lure on an anglerfish, powered by symbiotic bacteria, used to attract prey