Honors Marine Biology

Marine Mammals

December 6, 2012

Class Challenge

Bird Trivia Quiz

1. True/False: All birds have feathers and all animals that have feathers are birds.

2. True/False: Most birds have waterproof feathers, they have a special gland at the base of their tail that produces oil that they use to cover their feathers.

Bird Trivia Quiz

3. True / False: Like sea turtles, sea birds have salt glands that remove extra salts from their bodies.

4. True / False: There are two natural forces that a bird must overcome so that it can fly: Gravity and Drag.

Bird Trivia Quiz

5. True/False: A person who studies birds is called an Ornithologist.

Ocean Mammals• Mammals are a group of vertebrates (animals

that have a backbone). • Certain characteristics separate them from all

other animals: 1. mammals breathe air through lungs, 2. give birth to live young, 3. produce milk for their young, 4. are warm-blooded, 5. have hair or fur. 6. They also have relatively large brains 7. They have a variety of tooth sizes and shapes.

• More than 100 mammals depend on the ocean for most or all of their life needs.

• Marine mammals have all the characteristics of mammals, but they have different appearances and survival strategies.

• Marine mammals are divided into three orders: Carnivora, Sirenia and Cetacea.

• Within the order Carnivora are the pinnipeds (fin-footed mammals such as seals, sea lions, walruses), the sea otter, and the polar bear.

• Polar bears are closely related to bears like the grizzly, but are considered marine mammals since they have adopted a marine lifestyle.

Order Carnivora

Within the order Carnivora are:

1. The pinnipeds (fin-footed mammals such as seals, sea lions, walruses),

2. the sea otter, and

3. the polar bear.

The Harbor Seal

A walrus is easily recognized by its long tusks and great bulk.

Polar Bears

• Polar bears are closely related to bears like the grizzly, but are considered marine mammals since they have adopted a marine lifestyle

Order Sirenia

• The Order Sirenia is composed of manatees and dugongs (or sea cows)

Order Cetacea

• The order Cetacea includes whales, dolphins, and porpoises.

• Cetaceans are relatively large, generally characterized by streamlined bodies that glide easily through the marine environment.

• Whales, dolphins, and porpoises all belong to the same taxonomic order called cetaceans. The word cetacean is derived from the Latin "cetus" (a large sea animal) and the Greek "ketos" (sea monster).

• There are 86 species of whales, dolphins

and porpoises, collectively known as cetaceans.

• Most live in oceans and seas worldwide, both in open and inshore waters.

• Some dolphin and porpoise species can live in saltwater, brackish water, and freshwater, and a few species and populations only live in freshwater rivers and lakes. 

There are two categories of cetaceans:  (Fig. 7.9)

1. Baleen whales (mysticetes) are named for their feeding apparatus: a series of comb-like baleen plates that descend from the roof of the mouth.

Made of stiff, flexible material similar to human fingernails, baleen acts like a sieve, allowing the whales to strain food such as small fish, krill, and plankton out of the water.

There are 13 species of baleen whales ranging in size from the 6m pygmy right whale to the 33m, 120 ton blue whale, the largest animal on Earth.

While some species “sing”, baleen whales do not have echolocation abilities. 

2. Toothed whales, dolphins, and porpoises (odontocetes) are a diverse group of over 70 species which range in size from the 1.4m Hector’s dolphin to the 18m sperm whale.

They have well-developed echolocation which they

use to locate each other and to hunt fish, squid, and marine mammals.

Twenty-three cetacean species or populations are classified as Critically Endangered, Endangered, or Vulnerable, while many other local and regional populations are seriously depleted.

The population status and/or distribution of over a third of all cetacean species are unknown.

http://mikenish.com/FHL/?p=845

• Dolphins can use echolocation to help them find food or find their way from place to place. They make special clicking sounds.

• Scientists think the sounds can be aimed by the bulge at the front of the head which is called the melon.

• The clicks bounce back off any object in their path. Dolphins can tell the size, shape and direction fish are travelling in.

• This is very important in dark, murky seas when dolphins cannot see their prey. It means they can catch fish in total darkness.

Figure 7.13

• Dolphins: Deep Thinkers?: Echolocation test

• http://www.youtube.com/watch?v=51G83jaeNC4&feature

Dolphins in the Military• Everyone is familiar with security patrol dogs.

You may even know that because of their exceptionally keen sense of smell, dogs like beagles are also used to detect drugs and bombs, or land mines. But a dog would not be effective in finding a sea mine.

• Sea mines are sophisticated, expensive weapons that are designed to work in the ocean where they can sink ships, destroy landing craft, and kill or injure personnel. Sea mines are made so that they cannot be set off easily by wave action or marine animals growing on or bumping into them. If undetected, sea mines can be deadly, destructive weapons.

• But just as the dog's keen sense of smell makes it ideal for detecting land mines, the U.S. Navy has found that the biological sonar of dolphins, called echolocation, makes them uniquely effective at locating sea mines so they can be avoided or removed. Other marine mammals like the California sea lion also have demonstrated the ability to mark and retrieve objects for the Navy in the ocean.

• In fact, marine mammals are so important to the Navy that there is an entire program dedicated to studying, training, and deploying them. ($27 Million Dollars) It is appropriately called the Navy Marine Mammal Program (NMMP).

• Dolphin Lifesavers: Training for a Mission

• http://youtu.be/8JNrtFG4RU4

• In the Line of Duty - Military Mammals - CBN.com

• http://youtu.be/tv6PFcanyTE

• US Navy Dolphin & Sea Lion Program - CNN 8/6/2011

• http://youtu.be/IBOpFMcdzZc

• Navy's Dolphin Work Outsourced to Robots

• http://youtu.be/akV--UHyk3g

The Bends

• When people dive, they have to be very careful not to contract a potentially deadly condition known as the bends.

The bends, Decompression Sickness or Caisson Disease

Occurs when nitrogen bubbles in the blood

lodge in certain parts of the body. A bubble caught in a vital organ can be fatal.

Before much was known about decompression sickness, divers got bubbles lodged in their joints forcing them to “bend” over in pain.

Nitrogen in the Blood

• A diver breathes air from the scuba tank that contains approximately 79 % nitrogen and 21 % oxygen.

• The pressure of being underwater forces the nitrogen into the body’s fatty tissues.

• The longer and deeper the dive, the more nitrogen is forced into the tissues.

• For example, at 10 metres the partial pressure of each gas is doubled, so twice as much nitrogen is absorbed into the tissues as on the surface.

• At 30 metres, four times as much nitrogen is absorbed.

• When the diver comes to the surface; that is, moves from a greater pressure to lesser pressure, the nitrogen comes out of the tissues back into the blood stream.

• This is like a soda bottle being opened. The gas is kept in solution by the pressure under the cap; when this is removed the gas bubbles out.

Getting this nitrogen out of the tissues at the correct rate is the challenge for

divers.

• To prevent being “bent”, a diver must slow the rate of nitrogen coming out of the tissues.

• This is achieved by reducing the change in pressure by slowing the ascent, even stopping part of the way.

• With the soda bottle; if the cap is opened a fraction and the pressure equalizes slowly, there is little bubbling.

• It is this slow equalizing of the pressure, or decompression, the diver must go through during ascent to the surface.

• Most decompression stops are done three

meters below the surface, but if a diver had been very deep or underwater for a long time, then the stops might be ten meters, six meters, and then three meters.

• The longest decompression stop is at three meters because the greatest pressure change occurs in the top three meters of water.

• The time spent at each stop depends on the length and depth of the dive.

• A dive to thirty meters for thirty minutes would require a stop of three minutes at three meters, but a dive to forty meters for the same length of time would require a stop of fourteen minutes at three meters.

• This time spent decompressing can be unnerving for divers, a the surface is so close but the diver is not allowed to go up: the natural environment could kill!

How do marine mammals manage to not get the bends?

• While it is still possible to get some gas anomalies without compressed air, it is exceptionally rare and usually involves other issues being present. For diving marine mammals, they are diving with a set amount of air in their lungs, a volume that no matter how fast or slow they ascend will never expand beyond its original size at the surface, which means that since they have no way of "loading" their bodies with excess amounts of gases at depth, the partial pressures of the gases in the bloodstream will be negligibly similar along depth gradients

Homework

• Complete Module 7 Test

• Begin reading Module 8 pages 187 – 197

• OYO Questions 8.1 – 8.5

• Study Guide: define a-f and 2-11

• Complete Lab

• Quiz: Dolphin Anatomy

• Class Challenge: Picture of your pet