Practicle #5

Question 1

Ecdysozoa

Answer 1

Group of prostome animals.

Apomorphies: cuticular integument, open circulatory system, chitinous cuticle, jointed appendages for locomotion, chitinous exoskeleton, compound eyes

Question 2

Cuticular Integuments

Answer 2

Protect against injury/physiological stress

Ecdysis: process by which animal sheds cuticle in order to grow

Question 3

Nematoda

Answer 3

Roundworms

Culticle made of collagen, move by contracting longitudinal muscles

Question 4

Tardigrada and Onychophora

Answer 4

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

Question 5

Arthropoda

Answer 5

Likely 5 million species, compound eyes, jointed appendages, chitinous exoskeleton

Question 6

Compound eyes

Answer 6

Made of thousands of repeating units called ommatidia, detect movement, large field of view

Question 7

Jointed appendages

Answer 7

Allow to have a strong exoskeleton withough reducing movement.

Question 8

Chitinous exoskeleton

Answer 8

Provides protection, significant variation

Question 9

Crustacea

Answer 9

Marine invertabretes

Nauplius larvae, stalked compound eyes, 2 pairs of antennae, body has cephalon (head) and trunk (abdomen and thorax), breathe through gills

Question 10

Hexapoda

Answer 10

Insects

Wings for flight, loss of abdominal appendages, 3-segmented thorax, labium mouth part, varied development strategies/growth phases

Question 11

Hemimetabolous

Answer 11

Incomplete metamorphosis (3 stages)

egg –> nymph –> adult
ex. cockroaches, grasshoppers

Question 12

Holometabolous

Answer 12

Complete metamorphosis (4 stages)

egg –> larvae –> pupa –> adult
ex. butterlies, wasps, beetles

Question 13

Myriapoda

Answer 13

Centipedes and millipedes

Both: loss of compound eyes
Centipedes: venomous fanges
Millipedes: 2 body sections fused together

Question 14

Chelicerata

Answer 14

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

Question 15

Cephalothorax

Answer 15

In chelicerata

Head and thorax fused together, where the eyes and mouth and legs are

Question 16

Abdomen

Answer 16

Where digestions, reproduction, respiration, and excretion occur

Question 17

Chelicerae

Answer 17

First set of legs in chelicerata, above the mouth, used as fangs or for grasping

Question 18

Arachnida

Answer 18

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

Question 19

Pycnogonia

Answer 19

Sea spiders

Organs found in their legs

Question 20

Merostomata

Answer 20

Horseshoe crabs

Long telson, book gills for locomotion and gas exchange

Question 21

Deuterostomia

Answer 21

Complete gut, dorsal hollow nerve cord, ciliated bars and slits, notochord, post-anal tail, endostyle

Question 22

Echinodermata

Answer 22

Monophyletic, marine, oral and aboral surfaces, complete gut, pentaradial symmetry, calcareous exokeleton, open ambulacral grooves, water vascular system

Question 23

Pentaradial symmetry

Answer 23

5 parts around central axis, laraval stage is bilateral, non-centralized nervous system

Question 24

Calcareous endoskeletal plates

Answer 24

Also called ossicles, hard plates the cover the body, often form a “test”, can have bumps called tubercles and moveable spines, can produce pedicellariae

Question 25

Pedicellariae

Answer 25

Pincers used to grab and remove debris

Question 26

Ambulacral grooves

Answer 26

5 grooves which tube feet are aligned on - closed on urchins and cucumbers - open on sea stars

Question 27

Water vascular system

Answer 27

Series of canals and tube feet filled with water, comes in through the madreporite (skeletal plate) which acts like a water regulating valve

Question 28

Madreoprite

Answer 28

Skeletal plate, acts like a water regulating valve

Question 29

Crinoidea

Answer 29

Basal lineage of echinodermata Sessile or mobile, arms with ciliated grooves for suspension feeding, loss of external maderporite

Question 30

Asteroidea

Answer 30

Sea stars 5+ arms connected to central disk, madreporite on aboral side, feed by inverting their stomatches and secreting digestive fluids

Question 31

Ophiurodiea

Answer 31

Brittle stars and basket stars Usually live deep, tube feet without suckers, madreporite on oral side, highly articulated arms with vertebral plates

Question 31

Echinoidea and Holothuroidea

Answer 31

Sister taxa to echinodermata Abulacral groove running from oral to aboral pores

Question 32

Echinoidea

Answer 32

Sea urchins and sand dollars Fusion of skeletal plates, moveable spines

Question 33

Holothuroidea

Answer 33

Sea cumcumbers 10-30 retractable oral tentacles around mouth, elongate on oral/aboral asix, endoskeleton reduced, internal madreporite

Question 34

Hemichordata

Answer 34

Acorn worms Unique proboscis, excretes waste, digestive tract between mouth and esophagus (pharynx), perforated opening leads from pharyns to outside (pharyngeal bars/slits)

Question 35

Chordata

Answer 35

Pharyngeal bars/slits, notochord, post-anal tail, endostyle, dorsal nerve cord

Question 36

Pharyngeal bars/slits

Answer 36

Repeated opening goes into pharynx, water goes in mouth and out slits, later becomes gills in fish

Question 37

Notochord

Answer 37

Rod like structure extenting the length of the body, provides axis for muscle attachment, allows for undulaing movement, reduced in tunicates

Question 38

Post-anal tail

Answer 38

Helps with swimming

Question 39

Endostyle

Answer 39

Thickened ciliated groove on pharynx, moves food to gut

Question 40

Dorsal hollow nerve cord

Answer 40

Developed into brain and spine

Question 41

Cephalochordata

Answer 41

Lancelets. Live in shallow sand, filter feeds, burrow with posterior end, segmented bodies, large digestive cecum, cuccal apparatus

Question 42

Urochordata

Answer 42

Tunicates and salps Sessile or free-living, incurrent and excurrent siphon, enlarges pharynx

Question 43

Keystone species

Answer 43

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

Question 44

Trophic cascade

Answer 44

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