Marine Biology Exam 2

marine organisms

Phylum Porifera (sponges)

Phylum Porifera (sponges)

Simplest true multicellular animal forms

Aggregations of specialized cells

Few cell types, no coordination between cells, variable symmetry

No well defined tissues or organs

Sponge Body plan

No gut, poorly developed tissue layers, internal space, variable symmetry, spicules (bony pieces)

3 cell types – wandering cells (secrete spongin), pore cell (canals, chambers), choanocytes/collarcell (move water, capture food)

Phylum cnidaria

Corals, anemones, and jellyfish

Digestive cavity, radiant cavity, medusa or polyp body plan, often colonial, tissue organization

Phylum Cnidaria: Class Cubozoa

Box jellyfish/sea wasp

Excruciatingly painful, can be fatal

Common in Australia

Phylum Cnidaria: Class anthozoa

Corals, anemones

Medusa stage reduced or absent

Colonial forms secrete calcium carbonate or protein skeletons

Corals mostly colonial

Anemones mostly solitary

Phylum Mollusca

Diverse forms, external calcium carbonate shells, nervous and circulatory systems, cephalization, complete gut

Specialized organs: Radula (teeth), mantle (attach to shell), and foot (movement)

Phylum Mollusca: Class Gastropoda

snails, limpets, nudibranchs (shell-less)

single coiled shell, radula, benthic, variety of feeding strategies

Body plan is twisted up to 180 degrees (torsion)

Phylum Mollusca: Bivalvia

Mussels, clams, oysters, scallops

Hinged two piece shell, laterally compressed body with no head, no radula

Benthic

Filter feeders – filter plankton and organic matter using gills

or deposit feeders

Phylum arthropoda

Marine and terrestrial, 75% of animal species

Segmented, jointed body plan

Hard exoskeleton made of chitin and coated in lipids with paired muscles

Bilateral symmetry

cephalization

simple or compound eyes

Phylum arthropoda: subclass crustacea

shrimps, crabs, lobster, barnacles, isopods, amphipods

Phylum arthropoda: subclass crustacea: infraclass Cirripedia

Barnacles

Operculum (opening plates)

Cirri (legs)

Phylum arthropoda: subclass crustacea: order Decapoda

Crabs, shrimp, lobster

Phylum echinodermata

“Spiny skinned”, calcareous endoskeleton,

locomotion by water vascular system - internal water canals and tube feet

No head; oral and aboral sides

Phylum Echinodermata: Class Asteroidea

Sea stars

tube feet exert lots of pressure to pry open shells of shellfish

can regenerate limbs and body and longs as central disc survives

Phylum Echinodermata: Class Ophiuroidea

Brittle stars

Very flexible arms

Five arms, but can be sub branched

often in deep sea

tube feet trap zooplankton

Phylum Echinodermata: Class Echinoidea

Sea urchins and sand dollars

Short or long spines

Aristotle’s lantern - 5 jaws made up of calcium plates

Phylum Echinodermata: Class Holothuroidea

Sea cucumbers

Crown of tentacles: highly modified tube feet

Typically deposit feeders

Phylum Echinodermata: Class Crinoidea

Sea Lillies

Sticky tubes feet catch zooplankton

Phylum Chordata: Subphylum Urochordata

Sea squirts (benthic)

Salps (planktonic)

Barrel shaped body with ingoing and outgoing siphons

Tadpole like larvae have features similar to vertebrates

Annelids

segmented worms

Nematodes

C. elegant ~ typical nematode

closely related to arthropods, tardigrades

Soft body, no bones – essentially no fossil records

Phylum Mollusca: Class Cephalapoda

Octopus, cuttlefish, nautilus, squids

Physically largest invertebrates, “peak of invertebrate evolution”

Sucker lined arms, well developed eyes, sensitive nervous system, reduced/internal or missing shell, swim by jet propulsion

Highly intelligent, predators, masters of camouflage

Squid body plant

Elongated spear shaped head, skinny arms, might have additional feeding tentacles (tentacular clubs)

Complex internal organs, brain/nervous system, circulatory system, siphon and beak

Octopus body plan

Large head, large arms

Complex internal organs, brain/nervous system, circulatory system, siphon and beak

Cephalopod camouflage

chromatophores – pigmented, light reflecting cells

controlled by nervous system but rapidly enlarged/contracted by attached muscles

Cephalopod ink

Made of melanin and mucus, released from ink sac

Mainly serves as an escape mechanism to distract or confuse predators

Cephalapoda: Nautilus

Chambered shell with big body chamber, smaller chambers connected by tube

Siphuncle: tube of living tissue passing backwards through chambers

regulates buoyancy by changing proportions of gas vs water in each chamber

more than 90 tentacles with grooves and ridges that grip food and pass to mouth

Beak rips and tears

Lives up to 20 years

Can move into deeper waters to avoid predation but not below 800 m

Cephalapoda: Cuttlefish

Cuttlebone (porous rigid dorsal structure made of calcium carbonate) regulates buoyancy

Uses an osmotic pump for gas/water exchange of small ampullae adjacent to cuttlebone chambers

causes water to diffuse in or out of cuttlebone

Agnatha

Jawless fish

Cartilage skeleton, lack scales, lack paired fins

feed by suction using muscular mouth

~ 100 species total; 530 million years old; hagfishes and lampreys

Lampreys

41 species (half parasitic)

adults can live in freshwater or marine habitats

all species breed in freshwater

Hagfish

exclusively marine, benthic scavengers living in cold deep waters

Reduced eyes under skin

Eat invertebrates or dead fish, tunnel in, eat from inside out

slime when stressed or attacked as a defense mechanism

Chondrichthyes

sharks, rays, skates

Sharks

cartilaginous skeleton, moveable jaw, multiple rows of teeth (regrow), ventral mouth, paired lateral fins, scales (dermal denticles)

most are predators

basking shark is a filter feeder

big size range; less than 10 in to 50 ft

1000 species total

Manta rays

filter feeder with modified gills, also eat zooplankton

Skates and stingrays

eat benthic invertebrates (grinding plates in mouth) or filter feeders

modified dermal denticle - can be clipped, often venomous

Osteichthyes

Bony skeleton, fused jaws, single row of teeth, terminal mouth, paired lateral fins, true scales (fused with skin)

~28,000 species total

Bony fish reproduction

nearly all marine fish are oviparous and shed eggs directly into the water column (cod, herring, striped bass)

can also lay eggs in nests in the sediment (salmon)

or lay eggs on a hard substratum (sticklebacks, garibaldis)

spawning is the simultaneous release of thousands to millions of eggs (from females) and sperm (from males)

nest building fish usually have more elaborate mating behaviors - e.g. red coloration and jaw change in salmon

Cartilaginous vs bony fish

Different mouth placement, tail lobes, denticles vs scales, and gill slits vs operculum

Similar fin structure

Operculum

enable one way flow of water past gills

bony fish have more effective breathing (don’t need to swim to breathe)

in contrast, sharks must always be moving

Buoyancy in bony fish vs sharks

Bony fish have swim bladder; don’t need to keep moving

Sharks have W-shaped bundles of muscles (myomeres) that provided side to side body movement; forward motion created lift due to body plan/ asymmetrical tail; large fatty liver provides buoyancy as well

Reef fish

e.g. Sohal surgeonfish and clownfish

Demerol (benthic) fish

spend most their time on the bottom

sill swim up into the water to feed

can be very abundant in shallow, productive water

e.g. flounder and haddock

Pelagic fish

open water fish

can swim very fast

e.g. tuna, salmon, and sardines

Deep pelagic

myctophids “lantern fish”

~65% of deep sea fish biomass - food for tuna, salmon, etc

5-10 cm

photophores for feeding and mating

Adaptations required for swimming

Generating thrust, maintaining buoyancy, acquiring oxygen, temp regulation

Generating thrust

undulatory waves created by muscles

thrust is generated tangential to body

normal force causes fish to move forward

side force is wasted energy

Undulate elongated body swimming type

undulate the body in nearly equal waves

relatively inefficient swimming

e.g. moray eel

Strong caudal fin swimming

most movement is in tail fin

combine with stiffness of body

rapid swimming

aerodynamic - minimal disruptive turbulence at the posterior end of the fish

e.g. tuna

pectoral fin swimming

use of broad pectoral fins (plus tail fin) - slowly generates forward thrust

agile by slow swimming

disc shaped body contributes to high maneuverability

e.g. angelfish

tail fin swimming

awkward swimming

fish constantly tilt and turn but this aids in maneuverability; foraging and escape from predators

fins aid in stabilization

rounded form and shape not suitable for straight long distance swimming, but can provide bursts of acceleration

e.g. trunkfish

Body forms

Streamlined, stiff – efficient cruising

Disc or diamond shape, flexible body, fins refine movement – high maneuverability

Elongated body, strong flexible tail fin – rapid acceleration

most fish have forms that permit use of all 3 component functions to some degree

Mola mola (ocean sunfish)

Flaps dorsal and anal fins like wings

lumpy pseudo tail (clavus) serves as a rudder

Adaptations for high speed cruising in tuna

streamlined shape reduces drag

Keels and finlets reduce turbulence

smooth skins and small scales reduce frictional drag

groove into which fins retract

corselet: patch of rough scales to help organize flow, reduce turbulence

high percentage of aerobic muscle, high myoglobin, higher muscle temp

Gills

Have evolved to maximize oxygen acquisition

Counter current exchange mechanism – new supply of relatively deoxygenated blood is constantly exposed to more highly oxygenated water

maintenance of buoyancy

without buoyancy, fish would spend 10-60% of their energy on maintaining depth

natural buoyancy – total weight of fish = weight of water displaced by fish (reduces energetic cost)

sharks will generally sink to the bottom if not moving, whereas bony fish can float

Swim bladder

used to adjust a fish’s bulk density relative to seawater

marine bladder ~5% of total body volume in marine fish

physostomus - directly connected to gut; “gulp air” to inflate

physoclistous - diffuse gas via blood to inflate and collage, no muscular control (most bony fish)

Gas supply to swim bladder

gas bladder is regulated by a physiological process

gas retained by counter current exchange

temperature regulation

most fish are cold blooded, body temp within 1-2 ˚C of water

some fish (e.g. tuna, some sharks) increase temp of portion of body ~10˚C higher than water temp

In tuna, red muscles are heated to improve cruising performance

countercurrent heat exchange reduces heat loss (arteries flow opposite adjacent veins)

Features of reptiles

dry skin, covered with scales

eggs with leathery shells

ectotherms

Sea turtles

shell is fused to backbone, can’t retract head

salt gland for osmoregulation

nest on land

occur primarily in warm seas

herbivores, carnivores, omnivores, jelly fish eater

8 species

Loggerhead turtle

carnivore

regular nester on GA barrier islands

eats fish, crustacea, mollusks, echinoderms

strong beak like mouth for chomping things

Leatherback turtle

Up to 2 m, 1000 lbs

Lacks shell, has 7 prominent ridges of scale less skin

ranges into colder water; good thermal regulation due to large size, thick blubber, high oil content

eats lion’s mane jellyfish, has backward’s facing barbs in its throat

sea snakes

in the same family as cobras, mambas, and coral snakes

Indian and pacific oceans

~55 species

entire life at sea

paddle shaped tail

viviparous (young develop in eggs in mother)

some females can store sperm

carnivores

venomous

Marine iguana

1 species

vegetarian

good swimmer, but spends much time on land

endemic to Galapagos

threatened/vulnerable

Seabirds

feed exclusively in the ocean

four groups of seabirds

most cannot walk efficiently on land (except gulls) - adapted to flying or swimming

endotherms, webbed feet, salt glands for osmoregulation, drab coloration, carnivores, nest on land

Sea bird endothermy

facilitated by large size, waterproof feathers, dense feathering (often down)

seabird webbed feet

present in all seabirds

efficient swimming

reduced or absent hind toe, better for swimming, worse for perching

sea bird salt glands

birds drink seawater

salt excreted at up to 2x seawater salinity

kidneys function like humans

sea bird feeding styles

underwater diving, surface feeding, aerial piracy

sea bird nesting

nest in dense colonies in isolated areas because they are awkward on land and vulnerable to predators

pros: safety in numbers

cons: competition for food and nesting sites

most are monogamous and brood one egg at a time

penguin nesting colonies

can be up to millions of penguins on one island

usually retain the same mate for several breeding seasons

can use satellites to find colonies duet guano stains on ice

seabird syndrome

set of adaptation to deal with the need to nest on land, but feed at sea (food scarcity around nesting site)

longer lived, larger than land birds

small clutches, larger eggs

long incubation time

extended parental care

monogamy

unique investment in offspring

Tuberoses

includes albatrosses, shearwaters, petrels

stay months or years at sea

catch fish at surface

can glide for long distances; circumnavigations

Penguins

18 species

most adapted to life at sea

flightless, wings modified as flippers

incredible swimmer, clumsy on land

layer of fat underneath skin for insulation, dense waterproof feathers

solid bones for diving

Emperor penguins

Mate in Antarctic winter (May-June) - only species to do so

Female leaves for 9 weeks to feed on fish; returns just prior to egg hatching

male incubates egg, loses ½ of body weight, huddle

males then leaves for 3-6 weeks to feed

jointly care for chick for 8 weeks until summer (Dec.), chick then feeds itself

Pelicans

Includes pelicans, tropic birds, frigate birds, boobies, and cormorants

most have distensible gular sac between branches of lower mandible

large fish eaters, feed primarily on fish and squid, but also other inverts

elaborate and complex mating displays and pair formation behaviors

cormorants

flightless or flight limited (relatively short wings)

adapted for diving underwater up to 45 m

eat eels, fish, and even sea snakes

Gulls, terns

Includes gulls, terns, jaegers, skuas, auks (puffins and razorbills)

predators and scavengers

Atlantic puffin

agile diver while hunting (preys on small schooling fish)

lifespan ~30 years

remain at sea outside of the breeding season

Mammal characteristics

mammary glands

hair/fur

large complex brain

warm blooded (counter current exchange to retain heat)

breathe air

placental development and birth to live young

extended care of young

Order Carnivora: suborder Pinnipedia

Sea lions, seals, and walruses

Live primarily in cold seas

rest and reproduce on land

conserve heat with blubber, thick fur, and large body size

carnivorous - eat fish, squid

True seals

~18 species

ear hole (no flaps)

short, thick flippers; distinct digits; nails

hind flipper – tail like for propulsion (not maneuvering)

Sea lion

~15 species

ear flaps

long flippers; digits merged; no nails

hind limbs – large, webbed, can rotate and prop themselves up

Walrus

has tusks

Carnivora: sea otter

Smallest marine mammal

hind feet are modified flippers

can mate and reproduce in water

no blubber, rely on thick fur

feed on urchins, crabs, mussels, fish

North Pacific, from California to Alaska

keystone species

Order Sirenia

Sea cows

restricted to tropical waters

fully aquatic

have lost hindlimbs

swim with stroke of paddle shaped tail

only herbivorous marine mammal

lifespan ~80 years

Order Cetacea

Toothed whale – polyphyletic (multiple distinct clades); predators

Baleen whales – monophyletic (form a single evolutionary clade); plankton feeders

Used sound for echolocation, social interaction, and prey immobilization (?)

microbiomes distinct from seawater, share common bacteria with other marine mammals

Cetacean Anatomy

Elongated snout, vestigial digits, lost hindlimb

mammal like organs

convergent evolution with fish (streamlined shape, fins)

Blubber

Insulation, energy storage

thickness ranges from a few inches to 12 inches

Baleen feeding

continuous ram suspension feeder vs intermittent ram suspension feeders

toothed whales

teeth used to capture prey, not for chewing

eat fish, squid, seals, sea otters, and other whales

Sperm whale

up to 60 ft, 45 tons

primarily eat squid

can dive 3 km for 2 hours; slow heart rate to slow CO2 exchange

Common dolphin

8 ft/300 lbs

eat squid and fish

complex social structure

Echolocation

major evolutionary innovation in dolphins and toothed whales enable efficient prey capture

clicks produced in air sacs just below blowhole

fatty structure on forehead “melon” focuses/directs sound waves

reflections received via the lower jaw, passed to inner ears