Invertebrate Diversity Flashcards
Protostome vs Deuterostome
Protostome:
-spiral cleavage
-mouth develops first near site of blastopore and anus forms opposite
Deuterostome:
-radial cleavage
-coelom becomes ceiling
-anus develops first near site of blastopore and mouth develops opposite the blastopore
General characteristics of Sponges
-do not have tissues but have specialized cells
-free swimming larvae stage, sessile adult stage
-no nerves or muscles
-both marine and freshwater species
-mesophyll layer is where fertilization occurs
-water goes in through pores into central cavity (collar cells) and out through osculum
Characteristic of Cnidarians
-radial symmetry
-arise from two layers of tissue
-no internal organs or coelom
-cynidocytes: stinging cells on tentacles
-nematocytes: harpoon-like organelle within cnidocyte with pointed projectile and poison to stun and entangle prey
Ex: hydra in freshwater
Characteristics of Platyhelminthes
-flatworms
-bilateral symmetry
-some level of cephalization, anterior eye spots to detect light, chemoreceptors, simple brain
-follows protostome development, but lacks coelom (acoelomate)
-many are non-self fertilizing hermaphrodites
Ex: tapeworm
Characteristics of Nematodes
-roundworms
-lack segmentation
-most are very small (less than 2.5 mm) but can go up to 5 cm
-many are parasitic
-external layer is a cuticle with collagen
-some are hermaphroditic, some are self-fertilizing, some are dioecious
-follow protostome development, but have pseudocoelom filled with acellular fluid
Ex: C. elegans (terrestrial)
Characteristics of Mollusks
-contain muscular foot, visceral mass with internal organs, and mantle
-some have shell formation that can be internal (squid) or external (snail)
-Bivalves, Gastropoda, and Cephalopoda
-protostome development, but are coelomates (have true coelom)
-some are hermaphrodites (but are non-self fertilizing), but most are dioecious
Characteristics of Annelids
-segemented worms
-metamerism (true segmentation)
-protostomic development with coelom
-thin external cuticle, projecting hairlike extensions called setae/chaetae
-developed/complete digestive system
-some can produce asexually through budding, but most are either non-self fertilizing hermaphrodites or dioecious
Ex: Lumbriculus variegaturus
Characteristics of Arthropoda
-body segments
-jointed appendages
-respiration can have spiracles gas exchange occurs directly between the cells and air in trachea, gills (crusteans), book lungs, book gills
-some are hermaphrodites but most are dioecious
Arthropoda subphylum
Hexipoda
Six pairs of legs, three body segments, can be winged or not, usually have antenna attached to the head, abdomen contains reproductive structures.
Myripoda
Many legs, usually found in dead decaying matter in soil
Crustacea
Most are aquatic, but some terrestrial, have two body segments (head/thorax fused to produce a cephalothorax), breathe by use of gills
Chelicerata
Also have two body parts, have specialized, claw-life or fang appendages called chelicerae, don’t have antennae, have a second pair of appendages known as pedipalps, can have either gills or book lungs
Echinodermata
-spiny skin, pentaradial symmetry in adult form, bilateral symmetry in larval stages
-ONLY marine
-endoskeleton made of ossicles
-many have tube feet for mobility; water vascular system
-deuterostomes with a true coelom
-regeneration even when 75% of body is lost, but reproduction is usually sexual – some are hermaphroditic, some dioecious, asexual reproduction rare.
Ex: Starfish
Metamerism
True segmentation
Hermaphrodite
Referring to an animal where both male and female gonads are present in the same individual
Dioecious
Sexes are separate
Coelom
Body cavity between intestines and body wall
