Taxonomy - Eukaryotes - Part II

Porifera

sponges - simplest, most primitive phylum

porifera characteristics

• parazoa - no diplo or triploblastic

• assymetrical (only phylum)

• intracellular digestion

• reproduction - asexual and sexual

• asexual - fragmentation or budding

• sexual - hermaphrodites: release either sperm or eggs

porifera: suspension feeders

feed on particles in water

porifera: sessile

do not move

porifera: choanocyte

cells that have flagella, move water in and out of the sponge

porifera: spicules

sharp needle-like structures

Cnidaria

jellyfish, coral, hydras

Cnidaria characteristics

• diploblasts (metazoa)

• no coelom

• radial symmetry

• incomplete digestive tract - two way digestion

• sexual and asexual reproduction

• polyp (sessile) stage

• medusa (mobile) stage

Cnideria: nerve net

primitive nervous system

Cnidaria: cnidocytes

cells that have nematocysts (stinging structure)

Cnidaria: hydrostatic skeleton

helps locomotion

Platyhelminthes

trematodes, tapeworms, flatworms (can be parasitic)

Platyhelminthes characteristics

• triploblastic

• acoelomates - no coelom

• bilateral symmetry - cephalization (brain)

• incomplete digestive tract - two way digestion

• sexual (hermaphrodites) and asexual reproduction

• two nerve cords: collection of nerves, span the length of their bodies

Platyhelminthes: excretory system - protonephridia

collection of flame cells

Platyhelminthes: flame cells

aid in osmoregulation

osmoregulation

move substances across a membrane to and from the outside environment into the worm

protonephridia

flame cells that are in a bundle

Nematoda

round worms (not earthworms) and hook worms

Nematoda characteristics

• triploblastic - psuedocoelomate

• bilateral symmetry - no cephalization, nerve cords

• complete digestive tract

• wide range of reproduction - monoecious, dioecious, parthenogenic

• have exoskeleton cuticle that can be shed in a process called Ecdysis

Rotifera

rotifers - small microscopic animals

Rotifera characteristics

• triploblastic - pseudocoelomates

• bilateral symmetry - cephalization (small anterior brain)

• complete one-way digestion

• have a corona: has cilia to sweep food into mouth

• several types of repro

• have flame cells for osmoregulation

Annelida

most advanced types of worms

Annelida characteristics

• triploblastic - coelomates

• protostome - mouth forms first

• bilateral symmetry - cephalization: have anterior ganglia

• complete one way digestive tract

• many types of repro - hermaphrodies, regeneration

• circulatory system - closed circulatory system: blood is found in vessles and is pumped

Annelida: segmented worms

segmented body plan - repeated features

Annelida: metanephridia

glands for excretion and osmoregulaiton - work in tandem with blood vessels

Annelida: chaetae

hair-like bristles that aid in traction for movement

Annelida: Oligochates and Plychates

two commonly mentioned classes of annalids

Mollusca

octopus, slugs, squids, clams

Mollusca - characteristics

• triploblastic - coelomate

• protostome

• bilateral symmetry - cephalization only in some molluscs

• reproduction - most are dioecious (external fertilization)

• complete digestion tract - use a radula

• metanephridia for excretion - organ of bojanus

• circulatory system - both open and closed

• respiratory system - gills

Mollusca: foot

used for locomotion and anchoring

Mollusca: visceral mass

organs found Inside: digestive, nervous, excretory, repro, and respiratory organs

Mollusca: radula

tongue-like organ with teeth-like projections: shreds food and sweeps food into mouth

Mollusca: mantle

tissue layers that secretes the hard outer shell

Cephalopods

head-food mollusks

• octopi, squids, cuttlefish

• cephalization

• well developed nervous system

• closed circulatory system - only mollusc with a closed nervous system

• high mobility - high oxygen demand

Gastropids

“stomach foot”

• snails and slugs

• open circulatory system - hemocoel: open space inside a mollusk where blood can flow to surrounding tissues NOT the coelom

• cephalization

• torsion during larval stage - rotation of structures which brings the anus right above their head

Bivalves

• clams, scallops, oysters, mussels

• no cephalization

• suspension feeders

• shell made up of two hinged parted called valves

• open circulatory system - hemocoel

Arthropoda

insects, spiders, crustaceans (largest animal phylum)

Characteristics of Arthropoda

• triploblastic

• coelomate

• protostome

• bilateral symmetry - cephalization

• one-way digestion

• excretion via Malpighian Tubules - excrete uric acid

• open circulatory system - hemolymph instead of blood

• Respiratory systems - book gills (aquatic), book lungs (spiders), tracheal tubes (terrestrial)

Arthropoda Key Characteristics

• jointed legs

• chitin exoskeleton (ecdysis)

• Tagmata

• cephalothroax

• can be born as nyumphs or larvae

Tagmata

specialized segments in their body plan

Cephalothorax

term used to describe the fusion of head and thorax tagmata

• spiders and crustaceans

nymph

small version of larger adults form

larvae

undergo metamorphosis in a pupa (cocoon)

Insects

• six legs

• spiracles - openings on their exoskeleton for air

• tracheal tubes for respiration

• one pair of antennae

Crustaceans

• Lobster, crab, shrimp, crayfish

• Book Gills for respiration

• Cephalothorax

• two pairs of antennae

• Some use green glands instead of Malpighian tubules for excretion

• filter hemolymph

• located near base of antennae

Arachnids

• spiders, ticks, scorpions

• eight legs

• book lungs for gas exchange

• cephalothorax

• no antennae

Echinodermata

Starfish, Cucumbers, sea urchins

Echinodermata characteristics

• Triploblastic - coelomate

• Deuterostone

• Radial Symmetry as adults - central nerve ring with radial nerves

• Bilateral as larvae

• Complete one-way digestion

• open circulatory system

• asexual repro by fragmentation

• sexual repro by external fertilization

Echinodermata key characteristics

• water vascular system

• Podocyte

• have radial symmetry

Water vascular system

Hydraulic system used for movement, nutrient, and waste transportation, and respiration

• unique to echinoderms

• used for locomotion as well

Podocyte

cells that filter the bodily fluids in echinoderms

Chordata

• reptiles

• amphibians

• birds

• fish

• mammals

Chordates characteristics

• triploblastic - coelomate

• deuterostome

• bilateral symmetry - cephalization

• complete one-way digestion

• advanced closed circulatory systems

• sexual repro (most) some asexual repro

four key features of chordates

• notochord

• dorsal hollow nerve cord

• pharyngeal slits

• post-anal tail

Notochord

• flexible rod that provides structural support

• becomes vertebral column in vertebrates

Dorsal Hollow Nerve Cord

• develops into the central nervous system

• becomes the brain and spinal cord

Pharyngeal Slits

openings on the back of the mouth that develop into gills for fish and the jaw + inner ear in terrestrial chordates

Post-Anal Tail

• extension of the posterior end of the body

• used for swimming in fish

• absent in humans, but present during embryonic development

Dorsal

back side of animal

Ventral

towards the belly of an animal

Chordata main subgroups

Invertebrates and vertebrates

Vertebrates

have spinal cords enclosed in vertebrae

invertebrates

do not have vertebrae

Invertebrate groups

• Urochordata (tunicates)

• Cephalochordats (lacelets)

Vertebrates groups

• Fish

• Amphibias

• Reptiles

• Birds

• Mammalia

Types of fish

• jawless

• cartilaginous

• bony

types of mammals

• monotremes

• placental

• marsupials

Urochordata (tunicates)

• Have a tunic surrounding their bodies

• Adults ONLY have pharyngeal slits (no notochord, dorsal hollow nerve cord, or post anal tail)

• motile larval stage

• hermaphroditic and budding for repro

• benthic habitats

• sessile

• suspension feeders

What is a Tunic?

• made up of carbohydrates

• can vary in thickness

• surrounds tunicates

Cephalochordate (Lancelets)

• also called Amphioxi

• have all 4 characteristics even as adults

• no vertebrae

• pharyngeal slits are used for filter feeding

What is vertebrae made of?

• bone or cartilage

• protects spinal cord

In vertebrates, dorsal hollow nerve cord becomes…

spinal cord and rain

cranium

vertebrates have this to protect the brain

endoskeleton is made of…

bone or cartilage

Viviparous

offspring develop inside mother, receive nutrients from mother, birth young

Oviparous

egg laying

• you hatch from eggs outside the mother’s body

• yolk sac in the egg provides nutrients

Ovoviviparous

Youth hatch from eggs inside the mothers body

• birth young

• yolk sac in the egg provides nutrients

Two heart chambered animals

fish

three heart chambered animals

reptiles and amphibians

four chambered animals

mammals and birds

Chamber

refers to a ventricle or an atrium

ventricle

pumps blood out of heart

atria

receives blood

In a two chambered heart, it has…

one atrium and one ventricle, both give and receive deoxygenated blood

In a three chambered heart, there is…

two atria and one shared ventricle

• ventricle mixed with both oxygen rich and oxygen poor blood

In a four chambered heart, there is…

two atria and two ventricles

• 2 circuits: systemic circuit and pulmonary circuit

Characteristics of all fish

• gills

• lateral line

• two chambered heart

Types of fish

• jawless

• cartilaginous

• bony

What are gills?

modified pharyngeal slits used for respiration

Buccal pumping

forcing water from their mouths to pass onto their gills

Ram Ventilation

swimming with their mouths open to “ram” water onto their gills

lateral line

row of sense organs that detect movement, pressure, and vibration in water

Swim bladder

not present in all fish, filled with air to control buoyancy

All fish excrete

ammonia as nitrogenous waste product

Jawless fish characteristics

• no jaw or scales

• no bones (only cartilage)

• no swim bladder

• Oviparous - external fertilization

• Hagfish and Lamprey

Hagfish

secrete slime for defense

• considered vertebrates despite not having a complete vertebral column

Lamprey

Parasitic and use rows of teeth to latch on and suck blood

• have first stages of a vertebral column

Cartilaginous fish characteristics

• sharks and rays

• jaw and wide array of teeth - evolved from gill arches

• cartilaginous skeleton

• no swim bladder

• Ampullae of Lorenzini

• Cloaca

• Oviparous, Viviparous, Ovoviviparous

Ampullae of Lorenzini

sensory organ that detects the electrical field of living things

• used for navigation via the earth’s electromagnetic field

Cloaca

a single opening for excretion, digestion, and reproduction