Chapter 28: Invertebrate Diversity Flashcards
Protosome
multicellular organism whose mouth develops from a primary embryonic opening
Ex. An annelid, mollusk, nematode or arthropod.
Deuterostome
Organisms whose anus forms before their mouths in embryonic development
Ex. Echinodermata
Sessile
Sponge anchored in one place, cannot escape predators in this stage
Radial symmetry
Organism whose body parts radiate from a central body
Cnidarian characteristic
Coelum
internal body cavity space between digestive structures and body wall
Platyhelminthes or Cnidarians don’t have this
Mollusks, Echinodermata and Annelida do have this
Cynidocytes
In Cnidarians
Explosive cell on tentacles that could sting predators if needed
Have structures called nematocysts inside them
Nematocysts
A specialized cell in Cnidarians
Acts as defense and to capture food
Spicules
Sponges chemical form of defense
Bilateral symmetry
If split a body in half, the parts are the same on both sides
Flatworms have this characteristic
Dioecious
Male and female reproductive organs are in separate organisms
Hermaphrodite
An organism having both male & female parts in one organism
Metamerism
True segmentation
Segmented worms
Setae/chaetae
thin external cuticle, projecting hairlike extensions
On annelida
Spiracles
Characteristic of Arthropoda
Little holes where gas exchange can occur
Book lungs
Part of Arthropoda
Book gills
Part of Arthropoda
Pentaradial
part of Echinodermata
5 segments outstretched from inner circle
Hexipoda
Part of Arthropoda 6 pairs of legs 3 body segments can be winged or not, usually have antenna attached to the head, abdomen contains reproductive structures.
Myripoda
Part of Arthropoda
Many legs
usually found in dead decaying matter in soil
Sponges
Do not have tissues, do have specialized cells.
Have free-swimming larval stage; sessile adult stage
No nerves or muscles, but individual cells can sense and react to changes in the environment.
Both marine AND freshwater species
Cnidarians
Radial Symmetry Arise from two layers of tissue No internal organs or coelom Both marine and freshwater species Contain stinging cells on tentacles called cynidocytes. Cynidocytes have structures called nematocysts.
Cnidarian Life Cycle
Sexual Reproduction
Medusa and polyp stages
Asexual reproduction
Always a polyp
All generations are identical
Platyhelminthes (flat worms) characteristics
Bilateral Symmetry
Some level of cephalization, anterior eye spots (detect light), chemoreceptors, simple brain.
Follows protostome development, but lacks coelom
Many are non-self fertilizing hermaphrodites
Marine, freshwater, and terrestrial species
Platyhelminthes Life Cycle
Some are parasitic so develop from eggs to larvae inside humans
Nematodes characteristics
Also known as roundworms
Lack segmentation
Most are very small (less than 2.5 mm), but can go up to 5cm; species are freshwater, marine, terrestrial – many parasitic
Follow protostome development, but have a pseudocoelom filled with acellular fluid.
Some are hermaphroditic, some can self fertilize, some are dioecious (male/female)
External layer is a cuticle with collagen.
Mollusks characteristics
Contain a muscular foot, visceral mass with internal organs, and mantle - some have shell formation that can be internal (i.e. squid) or external (i.e. snail)
Three general classes: Bivalves, Gastropoda, Cephalopoda
Marine, freshwater, terrestrial
Protostome development, but are coelomates (have true coelom)
Some are hermaphroditic (most non-self fertilizing), but most are dioecious
Annelida
Segmented worms – metamerism (true segementation)
Found in marine, freshwater, terrestrial habitats
Protosomic development with coelom
Have thin external cuticle, projecting hairlike extensions called setae/chaetae
Developed/complete digestive system
Some can asexually reproduce through budding, but most are either non-self fertilizing hermaphrodites or dioecious
Arthropoda characteristics
Body segments
Jointed appendages
Respiration can vary some have spiracles gas exchange occurs directly between the cells and air in tracheae, gills (crusteans), book lungs, book gills.
Some are hermaphrodites, but most are dioecious
Freshwater, marine, and terrestrial
Arthropoda subphylum’s
Hexipoda
Myripoda
Crustacea
Chelicerata
Hexipoda
6 pairs of legs 3 body segments can be winged or not usually have antenna attached to the head, abdomen contains reproductive structures Ex. Bees
Myripoda
Many legs, usually found in dead decaying matter in soil
Ex. Centipede
Crustacea
Most are aquatic, but some terrestrial
have 2 body segments (head/thorax fused to produce a cephalothorax)
breathe by use of gills
Ex. Beetle?
Chelicerata
2 body parts have chelicerae don’t have antennae have pedipalps can have either gills or book lungs Ex. Scorpions
Chelicerae
specialized, claw-life or fang appendages
Pedipalps
a second pair of appendages, usually on front part of head
Echinodermata
Spiny skin, pentaradial symmetry in adult form, bilateral symmetry in larval stages
ONLY phylum of animal that is strictly marine
Endoskeleton made of ossicles (bone-like)
Many have tube feet for mobility; water vascular system
Deuterosomes with a true coelom
Regeneration happens
Reproduction is usually sexual – some are hermaphroditic, some dioecious
