Lecture 3 Flashcards
study for the midterm and final
Millions of years ago where did ancestors of marine mammals originally live?
On land but went back into the ocean and gained marine adaptations
What are some factors that affect how light acts in water?
- Depth
- clarity of water
What is the lens’ job?
Conrols how your eyes focus
- bends light rays to form clear image
What is a main problem with an amphibious eye?
- main problem, inflexibility
What happens when eyes that are adapted to air, see in water?
- Hyperopia or far-sightedness
- Focal point behind retina
What happens when eyes that are adapted to water, see in air?
- Myopic or near-sightedness
- focal point infront of retina
How are marine mammal’s vision anatomy different compared to land mammals?
What is unique about dolphins?
- stronger cornea in marine mammal
- Cornea resembles a fish cornea
- Dolphins have muscles to bend the cornea to focus above water (adaptation for both land and water)
What type of cell is mainly present in the retina of baleen whales, which ones are least present?
- Mainly Rods cell (photoreceptors only active in light)
- Less Cone cells
What part of the eye is present in only marine mammals? (what does it do?) (do humans have it?)
- Tapetum Lucidum
- reflective layer behind the retina that reflects light through the retina
- Humans DON’T have this layer
Do whales have tear ducts?
- No
- They have a gland in the cornea and have eye lids that secrete oily lubricating substances
How can sea otters see properly in both water and air?
- Do not dive deep, spend half their time on surface
- They have ciliary (eye) muscles that can bend the lens to aid them under water
Which species are monochromatic?
(what does monochromatic mean)
- Cetaceans
- Pinnipeds
- Monochromatic means they only have 1 light source to define colors)
How do the monochromatic species differ from most terrestrial mammals and humans?
- Most terrestial mammals are dichromatic
- humans are trichromatic
What adaptations protect marine mamalian eyes? (5 things)
- Clear membrane to cover eyes
- strengthened cornea
- continually produced tear film to protect eyes
- eyes are large and spherical
- Well developed tapetum
What are some facts about manatees’ vision/environment?
- Herbivores
- live in shallow waters
- small eyes
- dichromatic vision
How do neonatal seal’s vision/anatomy change during gestation(development)
- eyes positioned at the front of their heads
- by birth, eyes moved to the side of their face for wider FOV
What is unique about whales’ eyes
- eyes are so separated that they have a blind spot directly in front of them
What are the three parts of the hearing organs of ALL mammals?
- External ear or external auditory meatus
- Middle ear
- Inner ear
Which marine mammals have external pinnae and which do not?
- Some Pinnipeds (eared seals), Sea otters and polar bears HAVE Pinnae (external auditory meatus)
- Walrus, Earless seals and Sirenia have NO pinnae
What are the functions of Nares (nostrils) and Blow Holes. Which species have them?
- Nares or blowholes used for respiration and control water into the trachea
- Nares (nostrils) found in Pinnipeds, Sea otters and Polar Bears
- Blowholes found only in Cetaceans (Whales, dolphins, porpoises)
How are Nares and blowholes controlled in marine mammals?
- Opening -> contraction of skeletal muscles (active process)
- Closing -> Relaxation (passive process)
(energy conserving adaptation)
How do large cetaceans breath? What three versions of breathing exist?
Large Cetaceans - curl their body come to the surface and have their blow holes exposed
1. Spy-hopping (looking at surface)
2. Blowing at the surface
3. Diving (tail at the surface)
How do smaller cetaceans breath?
- leap out of the water
what are some selective species adaptations of Mysticetes (Baleen whales)?
- very friendly
- found in all oceans
- Females longer than males
- Can weigh up to 40,000 Kgs
- Extremely long pectoral fins
- Caudal fin with flukes
- serrated or jagged edge
- individual identifying underside patterns (dorsal black) and (ventral black-white mottled)
Why do Humpback whales have ventral pleats(folds)?
- Allows baleen to expand
- increase capacity of mouth when feeding
- Use of ‘bubble netting’
- surround prey, then lunge feed to maximize food intake
What is the body coloration of Delphinidae?
- Common dolphin -> dorsal darker, ventral lighter
- Killer whale -> bold black & white
- Commerson’s dolphin -> basic black or grey/white
- Can include stripes, capes, overlays, slots, blazes
What are some anatomical and behavioral features of Delphinidae?
- Dorsal fin -> pointed or falcate (sickle shape)
- Caudal fin -> has flukes symmetrical halves
- unique feeding adaptation
- opportunistic (help humans fish)
What is the only species that feeds on OTHER marine mammals
- Only cetaceans
- Feed on fish, sea turtle, birds, sharks, squid
What are two groups of populations and what do they eat?
Resident group
- specializes in eating fish (salmon)
Transient group
- mainly eats other marine mammals (seals, whales, dolphin)
