Bio Test 4

Phylum Annelida

Segmented worms

Characteristics of Phylum Annelida

• Made up of segments- subdivisions that partially transect the body cavity

• Live in marine, freshwater, and damp soil

• Passive filter feeders to voracious & active predators

• Bilaterally symmetrical, Protostomes, coelomates

• Have both circular and longitudinal muscles (hydrostatic skeleton)

• Closed circulatory system

• Alimentary canal

Nervous system of Phylum Annelida

• Brain like pair of cerebral ganglia in head

• Connects to a ventral nerve cord

• Have some combination of:

  • tactile organs, chemoreceptors, balance receptors & photoreceptors

Closed circulatory system of Annelids

• Blood is contained within vessels

• Dorsal and ventral blood vessels

• Linked down the length of the worm by pairs of vessels

• Five pairs of vessels that circle the esophagus pump blood throughout system

Respiration of Annelids

• Occurs through the skin via abundant, tiny blood vessels

• Blood contains oxygen-carrying hemoglobin

Excretory system of Annelids

• Each segment contains metanephridia

• Remove wastes from the blood and coelomic fluids

Metanephridia

Excretory tubes

Digestive system of Annelids

Alimentary canal

Gizzard

Stomach; Grinds up food

2 classes of Phylum Annelida

• Sendenteria

• Errantia

Sendentaria

Earthworms, leeches, Christmas tree worms

Errantia

Polychaetes (free moving worms)

Class Sedentaria

• Earthworms possess chaetae

• Earthworms are detritivores (recyclers)

• Most are hermaphrodites

• Some are predatory and others parasitic

Chaetae

• Bristles made of chitin

• Found on ventral side

• Used for movement (anchor)

What do earthworms play an important role in?

Soil building

Clitellum

Organ that secretes a mucus cocoon in which embryos develop (skin more smooth)

How do they digest?

Either make a cut or secrete enzymes that digest a hole in the skin (teeth-like structures)

What do Class Sedentaria secrete?

Hirudin (anticoagulant) and an anesthetic

What does Hirudin act as?

Blood thinner

What can leeches help with?

Reattachments or skin grafts

Class Errantia

• Polychaetes

• Each segment has paddle-like structures = parapodia

Parapodia

Paddle-like structures

What do parapodia aid in?

• Locomotion (each has several chaetae)

• Function as gills (lots of blood vessels)

Phylum Mollusca

Snails, slugs, oysters, clams, octupuses, & chitons

Characteristics of Phylum Mollusca

• Bilateral symmetry

• Protostomes

• Coelomates

• Soft bodied, but most are protected by hard shell

What is shell made of?

Calcium carbonate

Body plan of Phylum Mollusca

• Muscular foot (used for movement)

• Visceral mass

  • Contains most of the organs

  • Gonads - most species have separate sexes

• Mantle

  • Layer that covers like visceral mass

  • Typically secretes the shell

Mantle cavity

• Space between shell and mantle

• Houses gills, anus

Radula

• Rasping organ

• Scrapes food off surfaces

What type of circulatory system does Phylum Mollusca have?

Open circulatory system

• Heart pumps hemolymph through arteries to sinuses (body cavities)

• Body fluid that bathes tissues

Classes of Phylum Mollusca

• Polyplacophora

• Gastropoda

• Bivalvia

• Cephalopoda

Class Polyplacophora

Chitons

Class Polyplacophora characteristics

• Oval shaped marine animals

• Encased in a shell made of 8 dorsal plates

• Found on rocks along coast

• Foot acts like suction cup to grip to rocks

  • hold tight against predators

  • keep wet during low tide

• Herbivores

  • use radula to scrape algae

Class Gastropoda

Snails and slugs

Characteristics of class Gastropoda

• Most are marine but some freshwater

• Most have a singled, spiraled shell

• Slugs lack a shell or have a reduced shell

• Have a distinct head with eyes

• Most have radula to eat plants or algae, but some are predatory

• Most distinct characteristic = torsion

Torsion

Occurs during development, causes anus and mantle cavity to end up above its head (twist)

Where are eyes located?

Often at tips of tentacles

Class Bivalvia

Clams, oysters, mussels, scallops

Class Bivalvia characteristics

• Have two lateral shells

• Lack a head and radula

• Filter feeders

Class Bivalvia shell:

• Hinged together dorsally

• Closed via adductor muscle - very strong

Bivalvia filter feeders

• Pull water into shell via an incurrent siphon

• Passes across gills & mucus catches food particles

• Particles are then passed to the mouth via cilia

• Water exits shell via an excurrent siphon

How can clams and mussels move?

Use foot to burrow/ bury themselves

Class Cephalopoda

Squids and octopuses

Class Cephalopoda characteristics

• Active predators

• Strong beak-like jaws and a radula

• Closed circulatory system

• Well-developed nervous system and complex brain

• Very elaborate eyes = good vision

• Largest invertebrate = giant squid

• Can eject ink when threatened

What is the largest invertebrate?

Squid

How do they grab prey?

With tentacles (modified foot) and bite with a venomous saliva

How many tentacles do octopus have?

8 tentacles - suction cups

What do squids use their siphon for?

To fire a jet of water, which allows them to swim very quickly

• Water is squirted out of mantle cavity = jet propulsion

• Can direct siphon to control movements

How many tentacles do squids have?

2 tentacles, 8 arms

Nautiluses

Only remaining group of shelled cephalopods (60-90 tentacles, no suckers)

What does their ink consist of?

Melanin and mucus

Phylum Arthropoda

Crustaceans, spiders, insects

Phylum Arthropoda characteristics

• Bilateral symmetry

• Segmented Coelomates

• Alimentary canal

• Jointed appendages, hard exoskeleton

What are their jointed appendages and hard exoskeleton made of?

Chitin and proteins

Function of jointed appendages and hard exoskeleton

Protection and attachment site for muscles

To grow, what do they need to do?

Shed the exoskeleton

• Molting

• Energetically expensive

• Vulnerable to predators until new skeleton hardens

Phylum Arthropoda segmented body:

Head, thorax, abdomen

Phylum Arthropoda head:

• Well-developed sensory organs in head

• Compound eyes

  • composed of many independent visual units

• Smell receptors

• Antenna - touch and smell

What type of circulatory system does Phylum Arthropoda have?

Open circulatory system

• Hemolymph is propelled by the heart into sinuses surrounding the tissues & organs

What do terrestrial species have?

A tracheal system (extensive series of tubes) with openings to the outside called spiracles (ex. Hissing cockroaches)

Subphylum Chelicerata

Sea spiders, horseshoe crabs, scorpions, ticks, mites, spiders

What are Chelicerata named for?

Claw-like feeding appendages called chelicerae

What do chelicerae serve as?

Pinchers or fangs

Characteristics of Subphylum Chelicerata

• No antennae

• Simple eyes (single lens)

• Two main body sections - cephalothorax, abdomen

Two main body sections of Chelicerata

Cephalothorax and abdomen

Most modern chelicerates are in class ______

Arachnida

Class Arachnida

• Four pairs of legs

• Pair of pedipalps

• Chelicerae

Function of pedipalps

Function in sensing or feeding

Spiders

• Predators that make webs and are venomous

• Gas exchange occurs in book lungs

Where does gas exchange occur?

In book lungs - stacked plates with extensive surface area

Book lungs

stacked plates with extensive surface area

Ticks

Blood sucking parasites of terrestrial vertebrates

Mites

Usually very small, feed on fungi, plants, animals

Subphylum Myriapoda

Centipedes, millipedes

Characteristics of Myriapoda

All are terrestrial and have antennae

Class Diplopoda

• Millipedes

• Each trunk segment has 2 pairs of legs

• Eat decaying plant material

Class Chilopoda

• Centipedes

• One pair of legs per trunk segment

• Predators with jaw-like mandibles

• Have a pair of venomous fangs

Subphylum Hexapoda

Insects, relatives (most diverse)

Body plan of Hexapoda

• Head, thorax (3 pairs of legs), abdomen

• Wings - 1 or 2 pairs attached to dorsal thorax

• Antennae

• Compound eyes

Advantages of flight

• escape predators

• find food

• disperse

How do Hexapoda reproduce?

Separate sexes and internal fertilization

Major changes in appearance of an individual during development

Metamorphosis

Incomplete metamorphosis

• Young are called nymphs

• Resemble adults but are smaller

• Go through series of molts

• Final molt

  • reach full size, develop wings, become sexually mature adults

Complete metamorphosis

• Maggot, grub, caterpillar

• Have larval stage

• Larvae look completely different from adults

• Pupae

  • inside the pupa, the larva’s body completely changes into a fully grown adult

Subphylum Crustacea

Crabs, lobsters, crayfish, shrimp, isopods

Traits of Subphylum Crustacea

• Biramous (branched) appendages

• Two pairs of antennae

• Numerous mouth parts - 3 or more

• Have appendages on abdomen

• Two main body parts - cephalothorax and abdomen

What do biramous (branched) appendages specialize in?

Feeding and locomotion

Gas exchange in Crustacea

• Smaller species directly across cuticle (exoskeleton)

• Larger species have gills

Isopods

• Small feet and legs

• Micrograzers, micropredators, parasites, and detritivores

• Includes pill bugs, rolly pollies, wood lice

Desopoda

• Large crustaceans

• Cuticle on dorsal side is hardened by calcium carbonate

• Some are planktonic (zooplankton)

• Barnacles = sessile

What is a krill?

Small & shrimp-like, eaten by some whales

• Copepods (aka cyclops - single eye)

What are barnacles?

• Anchor to rocks, boats, whales

• Strain food particles out of water

• Cuticle hardened into calcified shell

Horseshoe crabs, spiders, scorpions, ticks, mites; Body having 1 or 2 main parts; 6 pairs of appendages (chelicerae, pedipalps, and 4 pairs of walking legs), mostly terrestrial or marine

Subphylum Chelicerata

Millipedes and centipedes; Distinct head bearing antennae and chewing mouthparts, terrestrial; millipedes are herbivorous and have 2 pairs of walking legs per trunk segment; centipedes have one pair of walking legs per trunk segment and poison claws on first body segment

Subphylum Myriapoda

Insects and springtails; Body divided into head, thorax, abdomen; antennae present, mouthparts modified for chewing, sucking, or lapping: 3 pairs of legs and usually 2 pairs of wings, mostly terrestrial

Subphylum Hexapoda

Crabs, lobsters, crayfish, shrimp; Body of 2 or 3 parts, antennae present, chewing mouthparts, 3 or more pairs of legs, mostly marine and freshwater

Subphylum Crustacea

Most closely related phylum to humans?

Phylum Echinodermata

Phylum Echinodermata

Sea stars, sea urchins, sea cucumbers

Characteristics of Phylum Echinodermata

• Deuterostome, Coelomates, bilateral symmetry (appear radial)

• Marine, slow moving or sessile

• Endoskeleton

• Alimentary canal

Endoskeleton

Internal skeleton made of calcium carbonate plates