bio lab prac 9 + 10

identify one characteristic of nematodes

• collagenous cuticle

• moves by contracting longitudinal muscles (undulating)

• decomposers)

economic importance of nematodes

can cause serious diseases e.g parasitic nematodes

2 apomorphies for onycophora, tardigrada, arthropoda

1. compound eyes

2. chitinous exoskeleton

3. jointed (articulated) appendages

4 major subgroups of arthopodas

1. chelicerata

2. crutacea

3. hexapoda

4. myripoda

3 apos of arthropods

1. chitinous exoskeleton

2. compound eyes

3. jointed appendages

adaptive sig of paired, jointed appendages in arthropods

• allow to have strong exoskeleton without reducing movement

3 apos of chelicerata

1. body has 2 functional units (cephalothroax, abdomen)

2. appendages used for walking are reduced in number

3. one set of appendage modified into chelicerae

definition of chelicerae

2 sets of anterior legs modified for defense + feeding

2 apos of merostomata

1. long telson (tail)

2. book gills (used for locomotion, gas exchange + flaps covering gills can be used for propulsion)

one apo for arachnida

1. 4 pairs of walking appendages

unique characteristic for spiders

spinnerets for silk production

unique characteristic for scorpion

telson modified into stinger for hunting prey and self defense

function of chelicerae in spiders

fangs

2 apos for crustacea

1. nauplius larvae

2. stalked compound eyes

3. 2 pairs of antennae

2 ways crustacea modified their appendages for a new function

1. appendages for barnacles sifting food particles from water (walking —> filter feeding)

2. chelipeds / claws in lobsters or crabs: modified their first pair of walking legs into chelipeds to grasp prey and defend from predators

what distinct feature does a millipede have that a terrestrial isopod does not?

loss of compound eyes

2 apos of hexapoda

1. loss of abdominal appendages

2. distinct 3 segmented thorax (always 3 sets of legs on thorax)

3. Labium (fusion of 2nd macillaxe/ part of the mount)

the 3 developmental strategies of Hexapoda

1. Hemimetabolous / incomplete metamorphosis

   • WHO: cockroach, grasshopper

   • 3 phases: egg, nymph, adult

   • NOTE: nymph looks like adult but NO functional wings or reproductive organs

2. Holometabolous / complete metamorphosis

   • WHO: butterflies, moth, beetles

   • 4 phases: egg, larvae, pupa, adult

   • NOTE: larvae and adult looks completely different

3. Ametabolous

   • WHO: silverfish

   • gradual increase in size

apo of myripoda

1. loss of compound eyes

apo for chilopoda (myripoda)

1. presence of venomous fangs

apo for diplopods (myripoda)

1. presence of diplosegments (segments of 2 body segments into one so, each segments has 2 pairs of organs and legs)

3 apos of echinoderms

1. secondary endoskeletal plates

2. calcareous endoskeletal plates

3. loss of cerebral ganglion

4. open ambulacral grooves

5. water vascular system

2 apos that unite all other echinoderms EXCEPT crinoids

1. having an oral surface that faces downwards

2. tube feet that have evolved suckers allow for locomotion (instead of just feeding)

What type of symmetry do all adult echinoderms have?

secondary pentaradial symmetry

what symmetry do larval echinoderms have?

bilateral symmetry

functions of pedicellariae

• pincers used to keep debris and settling larvae off the body

• defend against larger organisms

possible functions of tube feet in echinoderms

tube feet in echinoderms belong to the water vascular system where there are internal hydraulic canals with specialized tube feet that work together with ossicles (hard shell) for LOCOMOTION and FOOD GATHERING aligned along the open ambulacral grooves.

what is unusual about endoskeletal plates in echinoids

a supportive system of calcareous endoskeletal plates/ ossicles that form an internal “shell” called a TEST

• give rise to bumps and knobs called TUBERCLES

• also has some moveable/ fixed SPINES

where are tube feets in a holothuroidean

tube feets are aligned along the ventral (oral) surface

from what did sea cucumber tentacles evolve?

modified tube feet around the mouth where 10-30 of them are retractable oral tentacles to gather food

an apomorphy that Ophiuroidea and Asteroidea share

5 arms connected to a central disc

2 apos for ophiuroidea

1. tube feet with suckers

2. madreporite on oral side

3. highly articulated arms with vertebral plates

an apo shared by Echinoidea and Holothuroidea share

have ambulacral grooves running from the oral to the aboral poles INSTEAD of radiating out from the mouth area and ONLY on the oral surface

2 apos of Echinoidea

1. fusion of skeletal plates

2. moveable spines

3 apos of Holothuroidea

1. elongated on oral/ aboral axis

2. endoskeleton reduced to isolated ossicles

3. internal madreporite

2 apos shared by Hermichordata and Chordata

1. pharyngeal gills slits

2. a post anal tail

What apomorphy does an adult Urochordata only have

ONLY pharyngeal bars and slits

NO post anal tail, notochord, dorsal hollow nerve chord

what is the primary function of the pharyngeal bars and slits

Repeated openings goes into pharynx

- Water goes in mouth and out slits

- Later became gills in fish

2 apos of chordata

1. pharyngeal bars and slits

2. presence of notocord

3. post anal tail

4. endostyle

5. dorsal hollow nerve

an apo for CEPHALOCHORDATA

1. segmented arranged body muscles called myomeres

2. large digestive secum

3. buccal apparatus

2 apos for urochordata

1. incurrent and excurrent siphon (allows for continuous water flow in body)

2. enlarged pharynx