Test #2 Material

Phylum: Arthropoda

Phylum: Arthropoda (Crustaceans, Spiders, and Insects

General Characteristics Exoskeleton is segmented and has jointed

appendages

Exoskeleton internal skeleton made of chitin and protein can be thick and hard, or paper thin and flexible for protection and the attachment of muscles impermeable to water and strong

Molting must shed the exoskeleton in order to grow another one leaves the animal temporarily vulnerable to other animals

Arthropoda Sense and smell

has eyes, olfactory receptors, and antennae (touch and smell)

Open Circulatory System fluid inside is called

hemolymph (blood is the term to describe fluid in a closed circulatory system)

hemolymph is pumped by the heart into small arteries then into sinuses

the fluid re-enters the heart through pores

Early Arthropods

The earliest Arthropod were the trilobites. They lived in shallow seas.

Class Arachnida (scorpions, spiders, and ticks)

Nearly all ticks are blood sucking parasites

Mites live on a wide variety of hosts including other arthropods

Have a cephalothorax with six pairs of appendages Chelicerae

fangs with poison (used to attack prey and chew)

Pedipalps 4 pairs of walking

appendages

Spiders

Gas exchange (breathing) is done by using a book lung. Stacked plates that

exchange oxygen and carbon dioxide between the hemolymph and air

Silk webs are strung to catch prey (produced by abdominal glands called spinnerets) Webs are different

according to the species, and are always perfect on the first try.

Webs are also used for escaping predators and to wrap the eggs.

alimentary canal (yellow) blood vascular system (red) breathing system (orange) nervous system (blue) excretion system (green) reproduction system (white) set of silk glands (white at the

rear)

Feeding

As a spider chews, it spills digestive juice onto the torn tissue, then sucks up the liquid meal. –Yummy.

Other Classes

Class Diplopoda Millipedes Wormlike with legs (2 pairs per segment) Not 1000 legs Eat decaying leaves and plant matter

Class Chilopoda Centipedes Carnivores Head has antennae 3 pairs of appendages (not legs) Jaw-like mandible 2 legs per segment Have poison claws that paralyze prey and help with defense

Class: Insecta

Outnumber all other forms of life combined

Live in every terrestrial habitat and in fresh & salt water

26 orders of insectsEntemology- study of insectsThe earliest insect fossil is from 400mya

Insecta Body Structure

Many have 1 or 2 pairs of wings that are an extension of the body (not appendages)

Birds and bats have modified legs and arms for wings

Dragonflies are thought to be the first to fly

Bees, butterflies, and wasps have wings that are hooked together and move as a pair

Beetles use the top half of their wings for protection on the ground and the bottom half to fly

Internal Insect Anatomy

Body has 3 regions

1. Head-1 pair of antennae and one pair of compound eyes

2. Thorax- 3 pairs of walking legs

3. Abdomen-abdominal region

Physiology

Open circulatory system (hemolymph) Breathe through a tracheal system

Branched, chitin lined tubes that carry oxygen directly to the cells

Opens to the outside through

Spiracles-pores that open and close to regulate air flow and limit water loss

Nervous system has a pair of ventral nerve cords that meet in the head at the cerebral ganglion (brain)

Growing happens in two separate ways

Incomplete Metamorphosis Young resemble adults but

are smaller Series of molting occurs until

it is an adult Grasshoppers

Complete Metamorphosis Complete Metamorphosis Maggots, grubs, and

caterpillars Larval stages

Larva -> Pupa -> Adult Usually reproduce sexually

Crustaceans (Lobsters, shrimp, crab, and crayfish)

Have 2 pair of antennae3 or more pairs of mouth partsA lost appendage can be regenerated

Phylum: Chordata

Two existing classes Chondrichthyes

Cartilagenous fish 14 orders 50 families 810 species

Ostiechthyes Bony fishes 46 orders 437 families 23,500 species

•Sharks, skates, rays

•Cartilaginous – they have relatively flexible endoskeletons made of cartilage instead of bone

•Started with real bones, evolved to cartilage

•Jawed and paired fins•Respiration by 5-7 gill slits on both sides of their pharynx•No swim bladder or lung

Class: Chondrichthyes

•Very dense and sinks if it stops swimming

•This helps with breathing; water constantly passing over gills

•Rest on sea floor pump water through body with jaw muscles

•Eggs are fertilized internally•Male has claspers on pelvic fins that transfer sperm to female

•Oviparous – lay eggs that hatch outside mother’s body

•Ovoviviparous – eggs hatch in uterus and the babies come out after. Nourishment from eggs

•Viviparous – young develop in uterus and then are born. Nourishment comes from mom

•Reproductive, excretory, and digestive systems all empty into a chamber called a cloaca, then it is emptied through a single vent

Reproduction

•Largest sharks are (plankton) filter feeders•Most are carnivores

•Swallow prey whole or use powerful jaws and sharp teeth to tear prey into chunks

•Teeth probably evolved from scales

•Continually shed and replace teeth

•Tough leathery skin is covered with toothlike, dermal placoid scales arranged to reduce the turbulence of water flowing along the body surface•Short digestive tract

Sharks

•Eyes are lidless•Behind each eye is a spiracle – remnant of the first gill slit•Sharp vision, but can’t see colors

•Nostrils open into dead end cups (smell not breathing)

•Can detect electrical fields caused by muscle contractions of other animals

•Ampullae of Lorenzini – electroreceptors located on the sharks head

Senses

•Lateral line – runs along side, detects changes in water (minor vibes)

•No eardrums – whole body receives sound waves through water

•Detect prey from a kilometer or more away with their large olfactory organs

•Skates and Rays

•Are mainly bottom dwellers•Flattened teeth suitable for crushing hard shelled prey

•Enlarged fins that extend onto the side of the head•Manta Ray – largest species

•Venom gland in the tail of stingrays probably helps to deter predators

•Some rays have electric organs in the tail or fins that can stun prey with as much as 200 volts of electricity

•Their eyes and spiracles (openings for taking in water) are located on top of the head, allowing them to take in water for gill ventilation while being partially buried in sand•Skates normally have prominent dorsal fins while those of rays are absent or reduced in rays

Skate

Ray

•Chimaeras

•Sometimes called a ratfish

•Feed mostly on mollusks

•Venom gland in front of the dorsal fin

•Diverged from sharks

Class Osteichthyes

•Bony fish

•Marine and fresh water habitat

•Size ranges from 1cm to 6m long

•Make up all but 4% of fish species

•Bony fish have passed through several stages making the following changes:

1. A completely ossified internal skeleton with a stronger cranium

2. The transformation of the air-breathing lungs into a buoyancy-compensating device called a swim bladder.

3. The transformation of the asymmetrical heterocercal tail (seen in sharks and some primitive bony fishes) into the symmetrical and more efficient homocercal tail

4. The development of thin cycloid scales and ctenoid scales from the thicker ganoid scales

5. The loss of spiracles, development of stout spines in the fins and more efficient jaws

•Outside

•Skin is covered by flat, bony scales

•Glands in skin secrete a mucus (slimy) to reduce drag while swimming

•Lateral line – detects changes in water

•Respiration•Draw water over 4 or 5 pairs of gills

•Gills are protected by operculum

•Water to mouth to pharynx to gills by movement of the operculum

•Helps fish breath when stationary

•Swimming

•Swim Bladder – air sac that helps control the buoyancy of fish

•Gasses go back and fourth between the blood and swim bladder

•Helps fish conserve energy by staying still

•Flexible fins for maneuvering and propulsion

•Fastest fish can swim in short bursts up to 80mph•Reproduction

•Most are oviparous – lay eggs and fertilized externally

•Scales

•Cycloid

•Thin and overlapping permitting more flexibility•Grow as the fish grows, and in some species, show annual growth rings

•Found in the primitive bowfin and many teleosts

•Ctenoid

•Ctenoid scales are essentially cycloid scales with teeth at their posterior edges

•It is thought that these teeth help to reduce hydrodynamic drag during swimming•Found in many teleosts

•Ganoid

•Thick and non-overlapping

•Composed of bone overlaid with an enamel-like substance called ganoin

•This type of scale is also seen in the lobed-finned coelacanth

•3 Lineages of Bony Fishes

1. Ray-Finned Fishes

•Most familiar to us

•Fins are supported by long rays or spines

•Light flexible scales that don’t hamper motion•Example: Teleosts – salmon, tuna, rockfish, catfish, perch, moray eels, flying fish, scorpionfish and bass, trout, herring

Gar

2. Lobe-Finned Fishes

•7 species

•Paired fins that incorporate fleshy extensions from the body

•May have used lobes to waddle onto land

•Have not evolved much

3. Lungfishes

•Live in deep sea off Madagascar

•Have actual lungs and come to surface to gulp air