OCN 201 Biology Lecture 8

Marine AnimalsVERTEBRATES

The Animal Family Tree

Bilateria

Radiata

Ancestral Protist

Round Worms

Molluscs

Segmented Worms

Arthropods

Chordates

Echinoderms

Cnidarians

Ctenophores

Sponges

Flatworms

Placozoa

Chordate TreeInvertebrates Vertebrates

Animal with the following features:

• Notochord• Dorsal hollow nerve cord• Pharyngeal slits (originally for feeding, later modified)• Post-anal tail

What is a chordate ?

~4% of animals are chordates

salps

• Pelagic or benthic• Colonial or solitary

(or alternating)

• Suspension feeders

Tunicates

• Small, fish-like, suspension feeder

• Can swim, but usually stays partly buried (as adults)

Lancelets (cephalochordates)

Amphioxus

Chordate PhylogenyInvertebrates Vertebrates

A chordate with a vertebral column

95% of all chordates are vertebrates

What is a vertebrate ?

Vertebrate diversityAmphibians*

6%*Mammals*

9%*

Rep2les*13%*

Birds*17%*

Fish*55%*

Marine vertebrate diversityOther&3%&

Fishes&97%&

marine vertebrates ~= fishes

• Jawless fishes (Agnatha)

• Cartilaginous fishes (Chondrichthyes)

• Bony fishes (Osteichthyes)

The Major Fish Groups

Agnatha• No jaws; have

rasping mouths

• Earliest appearance of cartilaginous skeleton

• Body covered with skin (not scales)

• Parasites or Scavengers

Lamprey

Hagfish

• Sharks, Skates, Rays, and Chimaeras• Skeleton of cartilage• Earliest appearance of jaws• skin covered with dermal denticles (like

teeth)

• Carnivores or Planktivores

Chondrichthyes (Cartilaginous Fish)

• Planktivores (filter feeders) are largest • Gaping mouth with small or no teeth• Gill rakers• Manta Ray (7 m across!)• Whale Shark (up to >10 m long!)

Chondrichthyes: Planktivores

Manta Ray

PlanktivoresWhale Shark

Chondrichthyes: Carnivores

Cookie-Cutter Shark

Lateral Line System

sensing movement

• Ampullae of Lorenzini

• Detect very weak electrical signals given off by all living things

• Find food in/on sediments

Electrosensory (sharks and rays)

Cartilaginous Fish

• 22,000 species• From about 1 cm to 8 m• Surface to ≥ 8370 m• Most numerous, most diverse, most

successful of marine vertebrates

Osteichthyes (Bony Fish)

• Good sense of sight and smell (except where eyes secondarily lost)

• Auditory• Lateral Line System (water movement,

displacement of water / pressure)

Osteichthyes Sensory Systems

Herbivores

Herbivores (algae)

mouthfilter:gill rakers

gill opening

H2O

gut

Used by the most successful groupsSardines, anchovies

AnchoviesSardines

Planktivores (Filter Feeders)

CarnivoresParrot Fish

Tuna

Mola mola: Ocean sunfishUp to 1300 kg and 3 m tip to tip

Most Massive bony fish:

Feeds on gelatinous zooplankton

Bony Fishes

Chordate PhylogenyInvertebrates Vertebrates

Chordate PhylogenyInvertebrates Vertebrates

Ray-finnedfishes(Ac#nopterygii)Bonyfishes

(Teleostei)

Sturgeonsetc.(Chondrostei)

Car8laginousfishes(Chondrichthyes)

Lobe-finnedfishes(Sarcopterigyii)

Amphibians

Rep8les

Birds

Mammals

Coelacanths

Reptiles, Birds, and Mammals

• Loggerhead• Leatherback• Hawksbill• Olive Ridley• Green Sea Turtle

(Honu)

Sea turtles

> 2 m long up to 1300 lbs

5 cosmopolitan species

• Chelonia mydas• Adults herbivorous (macroalgae)• Can submerge for 2 hrs when

resting

• Eggs laid on beaches - 2 months to incubate

• Nesting females return to beach where born (natal beach)

Honu (Green Sea Turtle)

• Crocodile - one living marine species

• Sea snakes - 50 species. Venomous, no gills

Other Marine ReptilesTropical West pacific/Indian Ocean

Seabirds

• albatross, shearwaters• gulls and terns• pelicans, cormorants,

frigate birds

• penguins

Mammals

• Endotherms (warm-blooded)• Breathe Air• Have Hair• Live Young• Milk Production in Females

Features:

Marine Mammals (Class Mammalia)

Carnivora - polar bears, sea otter, pinnipeds

Sirenians - dugongs and manatees

Cetaceans - whales and dolphins

CARNIVORA

Enhydra lutris

Sea Otters

Ursus maritimus

Polar Bears

Pinnipeds (seals and sea lions)

Sirenians

• dugongs and manatees

• Herbivores - eat sea grasses

• Near shore inhabitants of warm tropical waters

• Only ~2300 alive today

• Stellar sea cow hunted to extinction

Cetaceans

Includes the whales, dolphins and porpoises

Two Cetacean Suborders:

• Mysticetes (11 living species) – large – baleen whales - filter feeders – 2 blowhole openings

• Odontocetes (about 67 species) – smaller – toothed whales, dolphins, and porpoises – 1 blowhole opening

Mysticetes (baleen whales)

Use complex vocalizations or “songs” for communication

Baleen (Mysticetes)

Humpback Bubble Net

Odontocetes (toothed whales)

Use squeals, chirps and clicks for communication, echolocation and

stunning of prey

Questions?