Practicle #5 Flashcards
Ecdysozoa
Group of prostome animals.
Apomorphies: cuticular integument, open circulatory system, chitinous cuticle, jointed appendages for locomotion, chitinous exoskeleton, compound eyes
Cuticular Integuments
Protect against injury/physiological stress
Ecdysis: process by which animal sheds cuticle in order to grow
Nematoda
Roundworms
Culticle made of collagen, move by contracting longitudinal muscles
Tardigrada and Onychophora
Sister taxa
Open circulatory system, appendages for locomotion, chitinous cuticle
Tardigrada: semi-aquatic, extremophiles, cryptobiosis (able to go into dormancy for long time)
Onychophora: velvet worms, found in leafy habitats
Arthropoda
Likely 5 million species, compound eyes, jointed appendages, chitinous exoskeleton
Compound eyes
Made of thousands of repeating units called ommatidia, detect movement, large field of view
Jointed appendages
Allow to have a strong exoskeleton withough reducing movement.
Chitinous exoskeleton
Provides protection, significant variation
Crustacea
Marine invertabretes
Nauplius larvae, stalked compound eyes, 2 pairs of antennae, body has cephalon (head) and trunk (abdomen and thorax), breathe through gills
Hexapoda
Insects
Wings for flight, loss of abdominal appendages, 3-segmented thorax, labium mouth part, varied development strategies/growth phases
Hemimetabolous
Incomplete metamorphosis (3 stages)
egg –> nymph –> adult
ex. cockroaches, grasshoppers
Holometabolous
Complete metamorphosis (4 stages)
egg –> larvae –> pupa –> adult
ex. butterlies, wasps, beetles
Myriapoda
Centipedes and millipedes
Both: loss of compound eyes
Centipedes: venomous fanges
Millipedes: 2 body sections fused together
Chelicerata
Sea spiders, horseshoe crabs, arachnids
Body has 2 units (cephalothorax and abdomen), appendages used for walking are reduced in number, one set of appendages modifies into chelicera
Cephalothorax
In chelicerata
Head and thorax fused together, where the eyes and mouth and legs are
Abdomen
Where digestions, reproduction, respiration, and excretion occur
Chelicerae
First set of legs in chelicerata, above the mouth, used as fangs or for grasping
Arachnida
Spiders, scorpions, mites, ticks
- Spiders have one set of legs for silk production
- scorpions have stinger
4 pairs of walking appendages, book lungs or trachea for breathing
Pycnogonia
Sea spiders
Organs found in their legs
Merostomata
Horseshoe crabs
Long telson, book gills for locomotion and gas exchange
Deuterostomia
Complete gut, dorsal hollow nerve cord, ciliated bars and slits, notochord, post-anal tail, endostyle
Echinodermata
Monophyletic, marine, oral and aboral surfaces, complete gut, pentaradial symmetry, calcareous exokeleton, open ambulacral grooves, water vascular system
Pentaradial symmetry
5 parts around central axis, laraval stage is bilateral, non-centralized nervous system
Calcareous endoskeletal plates
Also called ossicles, hard plates the cover the body, often form a “test”, can have bumps called tubercles and moveable spines, can produce pedicellariae
Pedicellariae
Pincers used to grab and remove debris
Ambulacral grooves
5 grooves which tube feet are aligned on
- closed on urchins and cucumbers
- open on sea stars
Water vascular system
Series of canals and tube feet filled with water, comes in through the madreporite (skeletal plate) which acts like a water regulating valve
Madreoprite
Skeletal plate, acts like a water regulating valve
Crinoidea
Basal lineage of echinodermata
Sessile or mobile, arms with ciliated grooves for suspension feeding, loss of external maderporite
Asteroidea
Sea stars
5+ arms connected to central disk, madreporite on aboral side, feed by inverting their stomatches and secreting digestive fluids
Ophiurodiea
Brittle stars and basket stars
Usually live deep, tube feet without suckers, madreporite on oral side, highly articulated arms with vertebral plates
Echinoidea and Holothuroidea
Sister taxa to echinodermata
Abulacral groove running from oral to aboral pores
Echinoidea
Sea urchins and sand dollars
Fusion of skeletal plates, moveable spines
Holothuroidea
Sea cumcumbers
10-30 retractable oral tentacles around mouth, elongate on oral/aboral asix, endoskeleton reduced, internal madreporite
Hemichordata
Acorn worms
Unique proboscis, excretes waste, digestive tract between mouth and esophagus (pharynx), perforated opening leads from pharyns to outside (pharyngeal bars/slits)
Chordata
Pharyngeal bars/slits, notochord, post-anal tail, endostyle, dorsal nerve cord
Pharyngeal bars/slits
Repeated opening goes into pharynx, water goes in mouth and out slits, later becomes gills in fish
Notochord
Rod like structure extenting the length of the body, provides axis for muscle attachment, allows for undulaing movement, reduced in tunicates
Post-anal tail
Helps with swimming
Endostyle
Thickened ciliated groove on pharynx, moves food to gut
Dorsal hollow nerve cord
Developed into brain and spine
Cephalochordata
Lancelets.
Live in shallow sand, filter feeds, burrow with posterior end, segmented bodies, large digestive cecum, cuccal apparatus
Urochordata
Tunicates and salps
Sessile or free-living, incurrent and excurrent siphon, enlarges pharynx
Keystone species
Species with a disproportionate impact compared to its abundance.
ex. Sea stars are vicious predators –> feed on muscles which are a competitor for space –> by eating muscles, there is more space for other animals to thrive –> increase biodiversity
Trophic cascade
When changes in the abundance of one species have dramatic effects on the rest of the ecosystem.
ex. Sea otters keep urchins in check –> less urchins = more biodivdersity –> orcas feed on sea otters –> without otters, urchins grow out of control –> decreased biodiversity
