Marine Vertebrates Flashcards
What are the Five families of Carnivora
- Otariidae: sea lions and fur seals i.e. eared seals
- Phocidae - true seals i.e. earless seals
- Odobenidae - Walruses
- Ursidae - polar bear
- Mustelidae - marine and sea otter
Top 3 are pinnipedia
What is a Stem group?
Astemgroup is a set of extinct taxa that are not in thecrowngroup but are more closely related to thecrowngroup than to any other
What is a Crown group
crowngroup - all organisms more closely related to it than to any other extant organisms
Insulation in Pinnipeds
Insulation (inverse conductance – consider thermal conductivity of water)
Reduced surface area for heat exchange
Dense hair covering
Fat deposits - not as effective as same volume of fur
Control blood flow e.g. Restrict blood flow to outer limbs to decrease heat exchange
A note on oxygen stores in pinnipeds
Storage in 3 compartments:
* Respiratory system* Lung volume* Concentration of oxygen in lung at start of breath hold
* Blood* Blood volume* Concentration of oxygen binding protein - haemoglobin
* Body musculature* Muscle mass* Concentration of oxygen binding protein – myoglobin
Diving in Pinnipeds
Nostrils close reflexively and kept closed by water pressure
Soft palate and tongue prevent water entering the oesophagus during feeding
High haemoglobin concentrations (3.5 x human)
Ability to reduce heart beat & metabolism to approx. 10 % and to divert blood
Ability to empty lungs prior to diving - decrease N2 absorption
Tolerate high CO2 and lactic acid concentrations
High myoglobin concentrations in skeletal muscles
Senses of Pinnipeds
Eyes - large and adapted to low light; black and white only
Have multifocal lenses and can see well in water and air (variability in curvature of lens)
Acute hearing - apparatus similar to other mammals (pup recognition)
Can communicate and echo-locate by underwater clicks
Whiskers - vibrissae: very sensitive, packed at base with nerves - detect in water vibrations: if removed prey capture reduced
Nutrition in Pinnipeds
Generally opportunistic feeders and are generalists
Prey item examples - Crustacea, squid, benthic invertebrates, (molluscs), fish, birds and other seals e.g. leopard seal
Teeth generally adapted to grasping not chewing (crab-eating seal)
Reproduction in Pinnipeds
Generally breed in early summer with males arriving first to establish territories
Females arrive impregnated from previous year and give birth to a single pup: lactation = 1 - 7 weeks
Females then mates; fertilised egg - blastocyst - dormant till first pup has grown-up then implants into womb - normal development
Specifics of Otariidae
Two families:
Otariinae (sea lions)
Arctocephalinae (fur seals)
General characteristics:
Ability to rotate their pelvis
Ability to bring flippers forward under the body enabling them to “walk” on land
Have pinna
Generally sub-tropical and tropical distribution
Dense fur consisting of guard hairs and thick under fur
large fore flippers for propulsion
Sexual dimorphism
Cannot dive for long periods – 5-10min
Specifics of the Phocidae
True / earless seals
General characteristics:
Lack of external ears (see name)
Inability to rotate their pelvis: poor on land
Use of pelvic appendages for propulsion
Small pectoral appendages held close to the body and used for steering
Excellent diving ability
Thin fur that does not insulate very well but have a well developed blubber layer
Generally not sexually dimorphic
(exception = Elephant seal)
Specifics of the Odobenidae
Only 1 species !
General Characteristics
The presence of large tusks
Ability to rotate their pelvis, so hind limbs
brought forward under the body (adults too
heavy to be supported by limbs on land)
Propulsion by pelvic or pectoral appendages
No pinna
Virtually naked skin often warty
Therefore blubber rather than fur used for
insulation
Specifics of the Ursidae
Only 1 species !
General Characteristics
Polar bears are found across northern Canada, Alaska, Greenland and Russia
Thick insulating fur as well as 10 cm blubber layer
Pure meat eaters feeding on whales and seals
Reproduction is high investment: 2 cubs, but lactate for 18 months – 50 % infant mortality in first year
>25 years old and are on the vulnerable list
Specifics of the Mustelidae
Only 2 fully marine species:
- Sea Otter - Enhydra lutris - Sea Otter (N. Pacific)
- Marine Otter - Lontra felina - Chile and Peru (little known)
NB - Even the European Otter (Lutra lutra) may feed in marine environments
General Characteristics: Sea otter
Feed on fish, shellfish and crabs in shallow subtidal environments using “tools”
Heavily exploited until 1911 (Fur Seal treaty)
Extremely dense fur – up to 200,000 per cm2 but no blubber layer
Grow to 2 m, up to 30kg, and are the smallest exclusive marine group
Can mate and rear young exclusively at sea
The Sirenia
Two families:-
1. Trichechidae - Manatees with 3 species
2. Dugongidae - Dugons with 1 species
The sub orders of Cetecea
The Mysticeti - baleen whales
The Odontoceti – toothed whales
The Mysticeti - baleen whales
Baleen plates: filter-feeding apparatus - plates of keratin with a brush-like inner boarder - characteristics vary between species
Have a symmetrical skull, 2 blow holes and are very large!
There are 4 families:-
1. Balaenidae - 3 spp.
2. Balaenopteridae - 6 spp.
3. Neobalaenidae - 1 sp.
4. Eschrishtiidae - 1 sp.
The Odontoceti 9 families
Physteridae- Sperm Whales (1 sp.)
Kogiidae - Dwarf Sperm Whales (2 spp.)
Ziphiidae - Bottlenose & Beaked Whales (19 spp.)
Monodontidae - Beluga and Narwhal (2 spp.)
Delphinidae - Dolphins (32 spp.)
Phocoenidae - Porpoises (6 spp.)
Platanistidae - River Dolphin ( 2 spp.)
Iniidae - River Dolphin (1 sp.)
Pontoporiidae - River Dolphin (2 spp.)
The Odontoceti
Toothed whales, number and size varies inter-specifically (67 species)
Possess a dorsally asymmetrical skull with 1 blow hole
Lactic acid – how tolerate it?
Lactic acid is toxic. Can cause tissue damage
Marine mammals have buffer…glycolytic enzymes e.g. lactate dehydrogenase (LDH)
Role of Autonomous Nervous System in Regulating Dive Response
Autonomic nervous system (regulates unconscious actions)
Parasympathetic nervous system- the rest and digestsystem: conserves energy as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract
Sympathetic nervous system: preparation of intense activity - the fight or flight response
The 2 different nervous systems of marine mammals
Divided into Central NS (CNS) and Peripheral NS (PNS)
- CNS = brain and spinal chord: PNS all peripheral nerves
- PNS neurones convert mechanical, chemical, electromagnetic signals into nervous signals - transmitted to CNS via afferent nerves
- Interneurones integrate info. - transmit to effector organs (e.g. muscles) via efferent nerve
What is the Encephalisation Quotient:
Encephalisation Quotient: Actual Brain size / Predicted Brain Size
Information and importance of a brain
- Brain shape as well as size
- Extent of brain surface folding important - index = the total perimeter : exposed perimeter of cerbral cortex = GI (Gyrification Index – degree of cortical folding)
Sensory adaptations of Pinnipeds
Pinnipeds - Muscles and a cartilage valve along the external ear canal function to close the ear canal to water
But inner ear similar to humans and land mammals….
Outer ear collects and directs sound >
Middle ear filter and amplifies >
Inner ear acoustic sound > electric nerve > brain
Marine mammals make noise
Mammals make noise with their larynx
Pinnipeds, baleen whales have larynx that makes noise.
Mysticetes only use larynx – it has a U-shaped fold (similar to vocal chords
Odontocete use larynx but with specialized air sacs (by blow hole) = whistles, clicks etc. Channeled through melon
Baleenwhales contract muscles in the throat and chest, causing air to flow between the lungs and the laryngeal sac. Alternating expansion and contraction of the lungs and sac drives air across the u-fold, causing it to vibrate and produce sound. Vibrations from the laryngeal sac maypropagatethrough theventralthroat pleats into the surrounding water as soundwaves. Changes in the laryngeal sac shape may alter the frequencyand/ or
amplitudeof sounds produced
Examples of adaptation specific to cetaceans
Cranium telescoping: results in multi-layered skull influencing the pathway of sound into the head
Attachment of auditory apparatus: not attached to skull but floats in an insulated environment important for echo-location
No air-filled outer canals: have specialised fatty tissue connection
The variable thickness of the basilar membrane influences the thickness of the cochlea spire which regulates what frequency of sound that can be detected
Visual detection in marine mammals 1
Match receptor pigment sensitivity - to match light environment e.g. open ocean cetaceans maximum sensitivity at the blue end of the spectrum
Increase density of photoreceptors
Enhance photon capture - by modification & thickening of the tapetum (reflective layer)
Visual detection in marine mammals 2
Visual acuity (ability to resolve fine details)
1. Focusing ability of the optic in the eye
2. Density of receptors in the retina
3. The connection between receptors
4. Processing of the signal in the CNS
The strength of the eye lens depends on:
1. Refractive index
2. The extent of lens curvature
Chemoreception in marine mammals
Chemoreception
Inverse relationship between adaptations to a marine existence
and development of olfactory senses
Absent or poor in cetaceans; rudimentary in sirenians;
aspect of behavioural ecology of pinnipeds
e.g. mating and pup ID
Tactile sensation in mammals
Cetacean are tactile, mostly so around blow-hole = air / water interface
Major tactile mechanism = vibrissae e.g. rostrum of cetaceans,
“whiskers” of pinnipeds & sea otters
Magnetic detection of marine mammals
Only really investigated in cetaceans due to large migrations in
great whales - probably utilise earth’s magnetic field
- Underlying mechanism not clearly understood but magnetite has
been identified in the brains of several cetacean species
What are the measures of intelligence?
Brain Morphology
Communication
-Language and Thought
-Syntax and Reference
Emotional intelligence
-Self-awareness, empathy and altruism
Imitation and Social Learning
Behavioural responses
What are the measures of intelligence?
Brain Morphology
Communication
-Language and Thought
-Syntax and Reference
Emotional intelligence
-Self-awareness, empathy and altruism
Imitation and Social Learning
Behavioural responses
General conclusion for lecture 8 (cognition)
Brain morphology suggests high intelligence
Observational science suggests relatively high intelligence
Mostly supported by tests but tests are sometimes bias or in appropriate
Intelligence appears to be directly associated to the need to form strong social bonds and networks to remain fit
What are “the bends” in dolphins?
Dolphins seem to adjust their heart rates as they dive to avoid decompression sickness, also known as the bends, which is caused by sudden changes in pressure. Human divers must avoid surfacing too quickly as the drop in pressure can force nitrogen bubbles into their airways and cause joint pain or even paralysis.
Male reproductive structures
Production and storage of sperm
The ratio of testes to body size does vary inter-specifically
Size of testis related to sexual behaviour – males competing for females with high copulatory rates - bigger testes
Odontocete have very high i.e. testes : body mass – 7-25 x higher than predicted for terrestrial mammals; seasonality in development
Dusky dolphins have the record = 8 % (of bd. Wt. = testes)
Humans invest about 0.08 %
Similarly in Mysticete – biggest Right whales > 900 kg testes
Penis – can retract into the body
Actual structure similar to terrestrial mammals
Female reproductive structures
Estrous cycle has two phases (similar to terrestrial) :
Follicular phase : estradiol → GnRH → FSH – follicle formation
Luteal phase: progesterone – inhibits ovulation, reduced contraction and enables pregnancy
Phases vary in length between species
Reproduction in Marine Carnivora
As long-lived :
-rates of reproduction are low
-low regeneration potential if populations are
impacted
-have low resilience to environmental perturbations
One of the universal features of reproduction in marine Carnivora is delayed implantation
The timing of the delayed implantations is the key in the event of the reproductive cycle which is controlled by photoperiod and nutrition
The time of implantations represents reactivation of the reproductive system after a period of quiescence – is species specific
Pinniped Reproduction
Distinctive features of pinniped reproduction include:
-Delayed implementation
-Highly seasonal and synchronised reproductive
cycles
-The production of a single pup
Male Pinnipeds –annual cycle of testicular regression and growth
Mean annual pregnancy rates between 0.5 and 0.9 appear to be normal
There can be annual variations which results from changes in population density and resource availability
Mating and breeding seasons are combined
Sea Otter reproduction
Do not return to land / ice for birth and reproduction is a-seasonal
Male otters do not appear to have any seasonal cycles
Sea Otters do have a period of delayed implantation but is highly variable.
Gestation is about 6-8 months. But the period of active foetal growth is more likely to be between 4.5 – 5.5 months
Time between reproduction cycles > 1y because the pups tend to be nursed for 4 – 8 months
Annual birth rates - 0.5 – 0.9, but generally sea otter reproduction biology is not well known
Polar Bear reproduction.
Reproduction cycles are dominated by the annual cycles of sea ice. The breeding season occurs between March and May
Delayed Implantation occurs for about 4 – 5 months ending when females reach their wintering dens during late September
Gestation is only 3 – 4 months and consequently the new offspring are fairly poorly developed at birth: Mean litter sizes of 1.9
The annual mean pregnancy = % of females in a population that are pregnant or lactating / gestation period in years 0.3 – 0.6
Interval between birth generally about 3.1 – 3.6 years (high infant dependency)
Threats to pinnipeds - Pollution
Pollution
1. Marine debris - ingestion and drowning
2. Toxic compounds (e.g. PCB’s and oil)
3. Sewage - introduction of pathogens
4. Radiation - cancers
5. Noise pollution - exclusion from
preferred habitats
Threats to pinnipeds – Culling / Hunting
Culling deemed unreasonable because of:-
1. Economics - culling usually heavily subsidised and no evidence to suggest less seals = more fish
2. Socially - no social or cultural reasons for culling (exception - some traditional hunters)
3. Scientifically - cannot predict cascade effects – fisheries must prove there is a benefit of culls not other way around
4. Humane - clean kills rare - pointless suffering
Threats to Cetaceans - culling/hunting
- Fisheries related: by-catch and prey depletion
- Noise pollution : e.g. exploration for gas etc
- Chemical pollution: -
a. Heavy metals
b. Organochlorines
c. PCB’s - Physical habitat destruction:-
a. Deforestation
b. River diversion and
habitat manipulation
c. Coastal development
d. Energy production e.g. barrages
e. Land reclamation e.g. for mariculture - Global environmental change: ozone depletion and global warming
Threats to Sirenia - culling/hunting
All sirenians listed as endangered or vulnerable by the IUCN
Exasperated by :-
1. Slow reproductive rate
2. Long gestation period
3. Slow growth rate
Several threats:-
1. Habitat destruction: often through development and land reclamation.
2. Hunting for :-
a. Meat e.g. Moslems pork substitute
b. Religious festivals e.g. Sri Lanka
c. Soles of sandals e.g. Red Sea
d. Oil - traditionally thought to be medicinal
e. Powered bone - medicinal
f. Dugong ivory - jewellery
g. Dugong tears – aphrodisiac
3. Power boat collisions - esp. Florida (200 per y-1).
4. Toxic algal blooms -respiratory problems.
What is a fish? and their thermal strategies
Any of numerous cold-blooded (poikilothermic/ectothermic) aquatic vertebrates of the class Osteichthyes (bony skeleton) or Chondrichthyes (cartilaginous skeleton), characteristically having fins, gills and a streamlined body.
THERMAL STRATEGIES
Based on stability of body temperature
o Poikilotherm – variable body temperature
o Homeotherm – stable body temperature
Based on the sources of thermal energy
o Ectotherm – environment source of heat form environment
o Endotherm – animal generates internal heat to maintain body temperature
Heterothermyoccurs inanimals which are able to switch from endothermy to ectothermy
Teleost (ray finned fish) morphology
The relationships between fish morphology, environment and lifestyle
An otolith, (oto-, ear + lithos, a stone) or otoconium is a structure in the saccule or utricle of the inner ear. It is comprised of a combination of a gelatinous matrix and calcium carbonate crystals. Otolith crystals are relatively dense and heavy - they are connected to the rest of the body by the sensory processes of the macular cells. In fish, otoliths can be used for age determination, showing rings of different growth summer/winter, like tree rings.
Fins supported by more complex skeletal and muscle arrangments – more control over swimming motion – can move backwards, hover mid watewr etc..
Swim bladder – secretory, reabsorption and storage – gas gland accumulates oxygen and nitrogen against a pressure gradient
Mackeral and tuna – no swim bladder ineffciency of swim bladder to adjust quickly to change sin pressure
Lateral Line System
Gelatin-filled tunnel containing clusters of nerve cells for detecting vibrations
-runs beneath skin along each side from tail to head
-detects reflections of bow waves off nearby objects, incl. other fish
Allows rapid movement near solid surfaces and tight schooling
General body forms in fish
Fusiform – many pelagic species, streamlined, e.g. tuna, herring.
Attenuate (sometimes ‘anguilliform’) – elongated, e.g. needlefish, eels.
Filiform - threadlike, e.g. pipefish, snipe eel
Globiform – spherical, e.g. puffer, lumpfish
Compressed dorso-laterally – flattened side-to-side, e.g. flounder, sole, plaice, butterfly fish.
Compressed dorso-ventrally (or ‘depressiform’) – flattened top to bottom), e.g. Sea moth, rays.
Early life stages (e.g. larvae, fry) of many fish are fusiform when pelagic - change shape as they mature.
Body form reflects habitat and lifestyle
Fish swimming styles
Fish swimming gaits can be divided into two functional groups:
(1) body-caudalfin gaits vs. (2) median-paired fin gaits
- involve undulation of the body and caudalfinto create thrust
- powered by one or moremedianorpaired fins, while the body is held rigid
Swimming Styles: (1) body-caudalfin gaits
Anguilliform – the full body wave creates a backward-facing “wall” that pushes against the water
Thunniform – all about thrust from the lunate tail. Has reduced drag compared to full body wave swimming.
Ostraciiform - Caudal fin oscillates - useful for odd-shaped fishes, e.g. boxfish and puffer fish
Swimming Styles: (2) Median-paired fin gaits
Labriform [wrasse-like] - pectoral fins beat – like rowing. Useful for fine maneuvering, e.g. wrasse and parrotfish
Balistiform – dorsal and anal fins undulate allowing the fish to move by sculling, e.g. trigger fish.
Amiiform – dorsal fin undulates. Good for stalking or moving without disrupting body musculature, e.g. oarfish, seahorse
Gymnotiform – anal fin undulates –
e.g. knife fish that produce and sense electrical impulses from their body
Reproductive strategies – periodicity and frequency
Semelparity – single event then die (e.g. Pacific Salmon are a semelparous species)
alifehistoryadaptationin which all of anorganism’s reproductive resources are focused on a single, large reproductive event, then it dies
Iteroparity - more common: repeated reproduction (e.g. Cod are an iteroparous species)
alifehistoryadaptationin which anorganism
producesoffspringseveral times over many seasons
Parental investment? Life history patterns determine how an animal’s energy intake is allocated - evolved to optimize tradeoffs between growth, survival & reproduction.
Classic tradeoff = larger eggs, fewer of them.
Reproductive strategies also based on spawning habits:
Non-guarders - open substrate spawners – scatter eggs, spawn in large groups
a. Pelagic spawners – schooling fish such as Tuna (Scombridae) and sardines (Clupeidae).
b. Benthic – eggs adhesive – stick to substrate or in long strings to attach to surface of substrate, sturgeons, carp, pike
c. Brood hiders -bury eggs, for example Salmon (build redds, bury eggs)
Modes of reproduction: sex determination
88% of teleosts = gonochorists or dioecious = either male or female at any one time.
Sex – determined genetically (Genetic Sex Determination - GSD) or by environmental conditions in early stage of development (Environmental Sex Determination - ESD). Sex in some teleosts determined by interaction of genes and environment [GxE].
Functional hermaphroditism – rare in other vert groups but about 2% teleosts (= 30 families)
In some gonochoristic species, the gonad initially develops as an ovary even in individuals that eventually become male [sequential hermaphroditism]
