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Chapter 14 (Edited) — Transcript

by Jeffrey Ashley · 3,275 words · 515 segments · language en · Watch on YouTube

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0:00Hello, I'm Dr. Jeff Ashley and welcome
0:02to chapter 14. Let's get started.
0:04Chapter 14 deals with animals of the
0:06pelagic environment. Remember the
0:09difference between pelagic and benthic.
0:11So pelagic are those organisms living
0:13within the water column, not on the
0:16seafloor surface or within it. That's
0:18the next chapter. So let's get started.
0:20So how can marine animals avoid sinking?
0:24Well, many of them may increase their
0:26buoyancy. And some of them do this
0:28because they have gas containers. Here
0:31are some sephalopods. And they use a
0:34rigid gas container to contain gas to
0:38control their buoyancy. They can fill
0:40these rigid containers or spaces with
0:44gas, which allows them to control
0:47whether they move upwards or downwards
0:49in the water column. For fish, many of
0:51them use swim bladders. Swim bladders
0:54can expand or contract depending upon
0:57the depth. Shallow water fish swim
1:00bladder gas composition is very similar
1:02to the atmosphere. However, a swim
1:04bladder oxygen concentration increases
1:07as the depth increases in water. Swim
1:10bladders can be filled a number of ways.
1:13One way is for fish, and you've probably
1:15noticed this, coming to the surface and
1:17gulping atmospheric air. They're filling
1:20their gas bladder directly through their
1:22esophagus. This is a rapid way of
1:25controlling buoyancy. Other fish like
1:27this tropical reef fish adapted such
1:30that it can do a slow buoyancy change.
1:33There is no channel directly from the
1:35esophagus to the swim bladder. Rather,
1:38in fish with no pneumatic duct like we
1:41saw in the upper depiction, all the
1:43gases must be added or removed through
1:45the blood, which requires much more
1:47time. We've mentioned this before that
1:49even if you're mobile, you still want to
1:52remain in the euphotic zone because
1:54that's primarily where the food is like
1:57phytolanton. So if you're a zop
1:59plankton, this is a primary consumer.
2:01You're eating phytolankton. And where
2:03are phytolankton? They're hanging out in
2:05the sunlit zone. So controlling the
2:08ability to remain there is imperative.
2:11Some zop plankton, as we saw before,
2:13produce some fats or oils to stay at
2:15that surface or near surface. Some do
2:19have the ability to swim. Remember the
2:21term necton. Necton are the swimmers.
2:25These are larger fish and marine
2:26mammals. We'll see them soon. In
2:29previous chapters, we spoke of these
2:31shells or tests, and these were
2:33primarily produced by zoplankton.
2:35They're highly abundant in oceans. So we
2:38spoke of two kinds the solicious tests
2:40and the carbonatous tests and we said
2:42that radolarens had silica tests and
2:44they're intricately ornamental. They
2:47have spikes on the test to increase the
2:49surface area to keep them in the
2:52euphotic zone for longer periods of
2:54time. Fors or foreignifers are small
2:58they're planktonic mostly abundant in uh
3:00benthically diverse as well. Uh they
3:03have calcium carbonate shells that are
3:06often chambered to allow them to float
3:09better. Here's a class of zoplankton
3:11called copapods and they're the most
3:14oceanabundant biomass in zoplankton
3:17categories. They are microscopic. They
3:19look like little shrimp and they have
3:22egg layers. If you were to collect a
3:24surface sample from a coastal area or
3:27open ocean, you would find an abundance
3:29of these organisms. Although their body
3:32types differ structurally and immensely.
3:35Again, take a look at some of the
3:36appendages here to keep them floating or
3:40within that upper surface layer that is
3:42lit. Krill is another type of zop
3:44plankton. Although this one is
3:46macroscopic, you can actually see it.
3:48They are crustaceians and they resemble
3:50little mini shrimp or larger copapods.
3:53Most grow no longer than 5 cm and
3:56they're abundant near Antarctica and
3:58they're critical in the Antarctic food
4:00chain. Other macroscopic zoplankton
4:03include snidarians. They have soft
4:05bodies and stinging tentacles. Two kinds
4:08are hydrozoan, the Portuguese manowar,
4:11and that uses a gas- fil float to remain
4:14at the surface of the ocean and to
4:16travel through winddriven transport.
4:18Skyazoan are jellyfish. They have soft
4:21low density bodies and they range from
4:23microscopic to actually 2 m in diameter.
4:26They move via muscular contractions. So
4:29here we see the pat Portuguese man of
4:31war and you might have seen this is very
4:32common in some periods of time on the
4:34east coast of the United States
4:36especially down south. And again it's a
4:38gas fil chamber and below are tentacles
4:41with pneumaticists which are stinging
4:44cells. Likewise, jellyfish. This Medusa
4:47has a bell-shaped top and also stinging
4:51strands of tentacles. Because of the
4:53adaptation to ward off predators by
4:55having stinging tentacles, it makes for
4:58a safe zone for some organisms. You can
5:00see here on the right an Australian
5:02spotted medus jelly, but it provides
5:04habitat on its bell, the non-sting part
5:07for juvenile fish. We said before that
5:09nectonic means swimmers. That includes
5:12fish, squids, sea turtles, and marine
5:14mammals. They swim by trapping water and
5:17expelling it, for example, like some
5:19squid. Or they swim by curving their
5:21body back and forth. There are very
5:24large number of mechanisms at which
5:26these necton or nectonic organisms
5:29provide movement for their bodies.
5:31Here's a depiction of squid mobility.
5:34They move by trapping water in their
5:35mantle cavity between their soft body
5:37and their pen-like shell. And then they
5:39jettison the water through their siphon
5:41for rapid propulsion. You've probably
5:43seen images of this before. It's a huge
5:45and very quick backward movement. For
5:48this species, that backward movement can
5:50be so rapid it can eject them from the
5:52water and fly them into the air,
5:54avoiding predators. Fin design is really
5:57important in fish. Fish had paired
5:59vertical fins as stabilizers. They also
6:02have paired pelvic fins and pectoral
6:04fins for steering and greater balance.
6:07Their tail fin or codle fin is for
6:10thrust. Fish have something called a
6:12lateral line. It has a network of
6:14sensors to detect water pressure
6:15changes. So a little bit about the
6:17anatomy of a fish here. Externally we
6:20have that lateral line which you can
6:21often see in many species as this
6:23discoloration and a clear line heading
6:26from the head to the tail.
6:28Here you have the different types of
6:30fins. On top we have the dorsal fins.
6:34Here just below the uh gills we have the
6:37pectoral fins and further below we have
6:40the pelvic fins. Back here near the
6:43fish's anus we have appropriately named
6:45the anal fin and here we have the codle
6:48fin. Movement is done by alternating
6:51contraction and relaxation of myomeirs
6:54on the opposite side of a fish's body.
6:56There are different types of motions
6:58depending upon the fish species. Let's
7:00take a look at some of these terms. In
7:03Athuna form, the codle fin provides the
7:05power. This is the back and forth
7:07motion. So, this is a view from the top.
7:10And this fin is most commonly used to
7:12propel high-speed fish. Seahorses and
7:15other species use anapform. These are
7:18undulations passing along the dorsal
7:20fin. This parrot fish is using labraform
7:24skulling with pectoral fins. And
7:27finally, this sunfish, one of the
7:28world's largest fish, uses ostracil form
7:32paired paddling by the dorsal and the
7:34anal fin. Fin design in fish species is
7:38variable. There are rounded codle fins.
7:42They are flexible and maneuver at low
7:44speeds. And there are truncate fins and
7:47fork fins useful for both maneuvering
7:49and thrust and speed. Lunate fins are
7:52rigid and there's little
7:53maneuverability. They're efficient
7:55propulsion for fast swimmers though like
7:57tuna, marlin and swordfish. Then there
7:59are heteroscal fins. They are
8:02asymmetrical and they provide lift for
8:04buoyancy such as in sharks. You can get
8:06a vibe for all of these different types
8:08of codle fin shapes and their
8:10description by this table. Better yet,
8:13you can Google some of these and see
8:14them in action. What about adaptions for
8:17finding prey? Well, one of them is
8:20mobility.
8:22There's two main mobility techniques.
8:24One is a lunger. A lunger waits for prey
8:27and then pounces. Great example is a
8:29grouper. These fish use mainly white
8:32muscle tissue to orchestrate this
8:34maneuver. Cruisers actively seek their
8:37prey like tuna and utilize mostly red
8:40muscle tissue. So here we see the two
8:42examples of a lunger and a cruiser.
8:45Another one that I often see when I'm
8:47scuba diving or snorkeling are
8:49barracuda, which are lungers. You can
8:52often see them just hovering and waiting
8:55for their prey. And if their prey passes
8:57by, they'll lunge very quickly. So,
8:59what's the difference between red and
9:01white muscle tissue? Well, red has
9:03smaller fibers than white. So, cru
9:06cruisers have much more red tissue. It
9:09has higher concentrations of myoglobin,
9:11the red pigment with oxygen affinity. It
9:14supplies more oxygen and therefore has a
9:16higher metabic metabolic rate for
9:18endurance. Lungers have little red
9:21tissue due to the lack of continuous
9:22movement. They need white tissue. It
9:25fatigues more rapidly, although provides
9:27them with quick bursts of speed to
9:29capture their prey. What about
9:31adaptations for finding prey via
9:33swimming speed? Well, speed generally is
9:36proportional to size. The larger you
9:39are, the larger you can swim. Some
9:42species can move very fast for very
9:44short periods of time, mainly to avoid
9:46predation. Most fish are coldblooded.
9:49That means their bodies of the same
9:50temperature as the environment. They're
9:52not fast swimmers. However, some are
9:54warm-blooded and they're found in warmer
9:56environments. Helps them capture prey.
9:58What about the deep sea necton? So, not
10:01benthic, but deeper in the ocean column.
10:04These are fish that mainly consume
10:05dictitis or each other because of the
10:08lack of abundant food. They often
10:10because this is a near dark or dark
10:12environment employ ways of seeing prey
10:15or attracting it. They employ
10:18bioluminescence
10:19which involves receptors on their body
10:23that are called phototofores in the dark
10:26deep water necton environment. Organisms
10:29often have large sensitive eyes. They
10:32have large sharp teeth, expandable
10:34bodies. Often they have hinged jaws and
10:37some of them use counter illumination to
10:39remain unseen. Here are some species of
10:42deep sea fish that we've probably seen
10:45before. They are almost alienike in
10:49character and properties. You can see
10:51those former characteristics I just
10:53listed coming through in many of these
10:55species. Here's an interesting one. This
10:57is a gulper eel and it was captured on a
10:59research cruise off the coast of San
11:01Diego. The dark area in the middle of
11:03this eel's body is its stomach, which is
11:06designed to block biolum luminescence.
11:10So, if they eat something that is
11:11bioluminescent, it acts as a cover. So,
11:15it's not going to give them away, and
11:17they will end up as prey items. Here is
11:19an angller fish. And we're probably
11:21familiar with this one because of the
11:23adaptation of this appendage to appear
11:27like a prey item. And it dangles it in
11:30front of its mouth to attract prey close
11:32to an ingestion site, its mouth. Again,
11:35the hinge jaw coming through here and
11:37large teeth. We can see in these species
11:39of deep sea fish. How do we avoid prey?
11:42Well, some fish like to school. And
11:44schooling involves this concept of
11:46safety in numbers. A school may appear
11:48as a single large unit and be more
11:50avoidable for predators because of a
11:54fear factor. Schooling maneuvers also uh
11:58confuse predators. Some species employ
12:01symbiosis which is two or more organisms
12:04mutually benefiting from this
12:05association. There's three main types of
12:07symbiosis. Commensulism, mutualism, and
12:11parasitism. Commensilism is when a less
12:13dominant organism benefits without
12:16harming the host. Here we see a great
12:18example of that with a lemon shark and
12:21the attached raoras on its body. The
12:23host, the lemon shark, is just a vessel
12:26and is not harmed by the raoras.
12:28However, the raoras are there to pick up
12:31any stray prey items that don't make it
12:33into the mouth of the shark. Mutualism
12:35is when both organisms benefit. Think of
12:38Nemo. Here we have the clownfish and the
12:41aneommy. Parasetism. The parasite
12:44benefits at the expense of the host. And
12:46here we see an example of that in the
12:48image below. Here we see an isopod that
12:50has attached itself to the head of a
12:52white tip soldier fish. Parasites can
12:54eat away at the dermal tissue of the
12:57host organism. Let's switch to marine
13:00mammals. Marine mammals have land
13:02dwelling ancestors. They are
13:04warm-blooded. They breathe air. Have
13:07hair or fur. They bear live young and
13:09they have mammorary glands for milk.
13:11Here are the major marine mammal groups.
13:14So starting with the class mamalia, we
13:17have three orders for marine mammals.
13:20Carnivora,
13:21serinia, and sataceia.
13:24We're going to take a look at organisms
13:26in each one of these orders. Let's start
13:29off with order carnivora. The
13:31characteristics of these organisms are
13:33they have prominent canine teeth. Such
13:36examples are sea otterters, polar bears,
13:38and pinnipeds, walruses, seals, sea
13:40lions, and furs seals. Sea otterters.
13:43They're cute, but they inhabit kelp
13:45forests in coastal eastern North
13:47Pacific. Extremely dense fur, but lack
13:50insulating blubber. They were hunted for
13:53fur in 1800s, but made a good recovery.
13:57They eat many types of marine organisms,
13:59and they've been known to use tools.
14:02They have high caloric needs. Polar
14:04bears have massive web paws, are
14:06excellent swimmers. They have thick fur
14:09and hollow hairs to keep them warm. They
14:11eat mostly seals. Walruses have large
14:14bodies as we know, and the adults of
14:16both genders, have these ivory tusks.
14:18Seals, also called earless seals or true
14:21seals. They differ from sea lions and
14:23furs seals though. So, what's the
14:25difference between seals and sea lions
14:27and furs seals? Seals lack a prominent
14:29ear flap. Seals have smaller front
14:32flippers. Seals have four flipper claws
14:36and they have different hip structures
14:38and different locomotion strategies.
14:40Let's move on to the order serenia. Here
14:42we have herbivores. They eat shallow
14:44water coastal grasses. Two organisms
14:47falling under this order are manatees
14:49and they live in tropical coastal
14:52Atlantic areas. They can grow up to
14:54around 4 meters and weigh more than 1360
14:57kg. In the Indian and Western Pacific,
15:01manatee cousins are called the dongs.
15:04Here we see West Indian manatees, which
15:06have a rounded tail fin and nails on the
15:09front flippers. And here we see an
15:11Indian Ocean dong, which has a flute
15:14tail fin similar to that of a whale and
15:16has no visible nails on its front
15:18flippers. These are slowmoving
15:20organisms. And one of the threats is
15:23actually recreational boat activity in
15:25areas where these organisms live. These
15:28are oxygen breathers. So they come up
15:30and breathe in oxygen. So they appear in
15:33shallow areas because they can't move
15:36very fast. If boats come by, they can be
15:39hit by propellers or the hull of the
15:41boat. The order satia. These include
15:44whales, dolphins, and porpuses. They
15:46have an elongated skull, and they have
15:49blow holes on top of their skull.
15:51There's few hairs. They have what's
15:54called a fluke, a horizontal tail fin
15:57for vertical propulsion. So here we see
16:00various members of the order satasa.
16:02They have adapted to be really fast
16:05swimmers. They have streamline bodies
16:07and specialized skin structures which
16:10are 80% water with a stiff inner layer.
16:13What about the capability of diving
16:15deeply in order to seek prey or avoid
16:17prey? These organisms use oxygen very
16:20efficiently. They're able to absorb
16:22around 90% of inhaled oxygen and they're
16:25able to store large quantities of that
16:28inhaled oxygen. They can also reduce
16:30oxygen consumption for non-critical
16:32organs. They have muscles that are
16:34insensitive to the buildup of carbon
16:36dioxide and also collapsible lungs.
16:39Their avoli tiny chambers in the lungs
16:42facilitate gas exchange with blood. So
16:44unlike humans which cannot dive deeply
16:47without getting nitrogen narcosis or the
16:50bends these organs organisms can dive
16:53deeply in the order satasa there's a
16:56suborder called odontocetti
16:59these are the tooththed organisms like
17:01dolphins porpuses killer whales and
17:03sperm whales they use echolocation to
17:06determine distance and direction of
17:07objects and also to determine the shape
17:10and the size. What's the difference
17:12between a dolphin and a porpus? Porpuses
17:14are smaller, more stout body shape. They
17:17have a blunt snout, triangular, smaller
17:20dorsal fin, and blunt or flat teeth. On
17:23the other hand, dolphins have larger and
17:25more streamline shapes to them. They
17:28have a longer rostrm, and they have a
17:31falcate, a torsal fin, meaning it's
17:34hooked, and they have pointy teeth like
17:36killer whales. Just like we talked about
17:38sonar, echolocation is similar. Sound is
17:40reflected returned to the animal and
17:42interpreted. However, increased noise in
17:45the marine environment due to shipping
17:48or wind energy production may affect
17:51echolocation. Echolocation provides good
17:53vision for marine mammals that are
17:55limited by ocean conditions. Dolphins
17:57and porpuses also can emit sounds from
18:00their blowhole. Sound passes through
18:02their melon, an organ on the skull. The
18:04tooth whales will send sound through
18:06water. An evolved inner ear structure
18:08may help tooth whales pick up sounds.
18:11Whales can force air through their nasal
18:13passage and click travels through their
18:16organ. Whales can force air through a
18:18nasal passage and provide a clicking
18:20noise that travels through that organ.
18:22Tooth whales have large brains relative
18:24to their body size. They communicate
18:27with each other using sound. Their
18:29brains are highly convoluted. However,
18:31they're trainable. Wild dolphins have
18:34assisted drowning humans in oceans. The
18:36suborder Mysti includes baileine whales.
18:40Also includes the blue whale, finback
18:42whale, humpback whale, grey whale, and
18:44right whale. They have fibrous plates
18:46called baine that siv prey items. They
18:49use vocalize sounds for various purposes
18:51like communication. Here we have an
18:53image of baine. These are plates in
18:54whale mouths instead of teeth. And as
18:57the whale fills its mouth with water,
18:59the baine traps fish, krill, and
19:01plankton. Here we see a rack of baine
19:03from a bottom feeding grey whale. Grey
19:05whales are short, coarse baine, no
19:07dorsal fin, and their bottom feeders.
19:10Write whales have long fine baileine,
19:13but no dorsal fin either. The North
19:15Atlantic and the North Pacific Wright
19:17whales are the most critically
19:18endangered whales currently in the
19:20world. How can they use baine? Well,
19:21humpback whales feed at the surface,
19:23creating this bubble net. They fill
19:25their mouths with body weight of water
19:28and also prey. Grey whales can undergo
19:30long migrations, 22,000 kilometers
19:34annually, migrating from coastal Arctic
19:36Ocean to the Baja, California, and
19:39Mexico areas. Their feeding grounds in
19:41the Arctic during the summer months.
19:43Breeding and birthing grounds occur in
19:45tropical eastern Pacific in the winter.
19:48Most grey whales migrate. There's a
19:50resident population of about 200 that
19:53stay along the Pacific coast. They take
19:55advantage of food from coastal
19:56upwelling. There are fewer whales now
19:58than before whaling. That instigated the
20:01International Whaling Treaty. Hunting of
20:03grey whales was banned in 1938 and the
20:06grays were removed from the Endangered
20:08List in 1993 as populations rebounded.
20:11In 1948, the International Whaling
20:14Commission, the IWC, was established to
20:17manage whale hunting. In 1986, 72 IWC
20:21nations ban whaling altogether. However,
20:24there's three ways to legally hunt
20:26whales now. objection to the IWC ban,
20:29scientific whailing or Aboriginal
20:32subsistence whaling. In this chapter, we
20:34looked at pelagic organisms and it was a
20:37rough overview. I really want you to get
20:40the classifications down and some
20:42examples from each one of the
20:44classification groups. I also want you
20:46to understand some of the adaptations
20:48and behaviors. I'm going to provide you
20:50with some videos to watch from some
20:52documentaries, just some snippets to get
20:55an appreciation for some of the things
20:56that we saw such as schooling and also
21:00echolocation.

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