Ecdysozoa Lab - Bio 2

Clade Ecdysozoa - Ecdysis means molting (change in size/form)

Includes:

Phylum Nematoda

Phylum Tardigrada

Phylum Onychophora

Phylum Arthropoda

Phylum Nematoda (Roundworms)

Bilateral

Triploblastic pseudocoelomate ("false" body cavity that is partially lined by mesoderm)***

Protosomes (Mouth first)

Ubiquitous (Exists everywhere)

Phylum Nematoda - Characteristics

Some are free-living; most are parasites

Adaptations for parasitic life:

-> Thick Cuticle

-> Abundance of reproduction structures***

-> Reduced digestive system***

-> Reduced sensory structures

Typically dioecious (Separate male and female)

Phylum Nematoda

Turbatrix aceti (Vinegar eel)

Free living

Random Movement

Only possesses longitudinal muscles (lacks circular motion)

Phylum Nematoda

Ascaris (Human intestinal roundworm)

Parasitic

Dioecious (Separate male and female)

Dimorphic (Males and females look different)

-> Males have a hood at the end and are shorter than females

Ascaris (slide)

Reproductive organs

Pseudocoelum

Longitudinal muscles

(Female has the larger circles)

Phylum Nematoda

Trichinella spiralis - encysted in pig muscle

Larval worm - Darker circles

Cyst - Part surrounding the larval worm

Phylum Nematoda

Dirofilaria immitis - dog heartworm

Blood slide

Phylum Tardigrada (water bears)

Small, bilateral, protosome, true coelom visible

Cuticle - Rigid, non-living exoskeleton made of chitin***

Segmentation and lobopodal (unjointed) legs***

Open circulatory system - Body cavity (hemocoel) filled with fluid to transport blood/oxygen***

Tun state - Survive extreme temps, pressure, radiation***

Dioecious - Females can undergo parthenogenesis, where they can become pregnant without fertilization

Phylum Arthropoda

Bilateral

Triploblastic eucoelomate (true body cavity completely lined by mesoderm)

Protostomes

Largest phylum on Earth

Arthropod Characteristics

Cuticle made of chitin***

Segmentation & jointed appendages - a pair on each body segment (they have joints)

Open circulatory system - Heart pumps hemolymph (instead of blood) through open spaces (hemocoel)***

Subphylums of Phylum Arthropoda

Subphylum Myriapoda

Subphylum Chelicerata

Subphylum Crustacea

Subphylum Hexapoda

Subphylum Myriapoda - Centipedes and Millipedes

Unbranched (uniramous) appendages and a single pair of antennae

Class Diplopoda (millipedes)

-> 2 pairs of legs per segment

Class Chilopoda (centipedes)

-> 1 pair of legs per segment

-> Poisonous claws behind head

Subphylum Chelicerata - Spiders, Horseshoe Crabs, Scorpions

Cephalothorax and abdomen regions

Six jointed appendages

Manipulation of food, locomotion, defense, and copulation

-> Chelicerae - first pair (Modify to fangs)***

-> Pedipalps - second pair

All others are used as legs

Subphylum Chelicerata - Class Merostomata and Arachnida

Class Merostomata (horseshoe crabs)

-> Living fossils - around for 350 million years

-> Book gills = highly folded gills***

-> Compound and simple eyes

Class Arachnida (spiders, scorpions, ticks, mites)

-> Some have modified chelicerae into fangs - inject venom

-> Book lungs = highly folded lungs***

-> Spinnerets - secreting silk

Subphylum Crustacea - Crabs, lobsters, crayfish, shrimp, and barnacles

Cephalothorax and abdomen

-> Biramous appendages - two jointed branches from a single base

Two pairs of antennae

Mandibles = jaws

Two pairs of maxillae = hold and manipulate food

Subphylum Crustacea

Class Malacostraca

Order Decapoda (10 legs; lobsters and crayfish)

Cephalothorax covered in carapace = hard chitin covering

-> Maxillipeds - appendages on 1st 3 segments

-> Chop food and pass to the mouth

-> Chelipeds - 4th segment

-> large pinching claws

-> Large four segments = walking legs

-> Dioecious

-> Swimmerets = used for swimming and holding eggs in the females

-> Swim backwards

Crayfish External Anatomy - Top View

Top View

-> Rostrum - In front of the eyes***

-> Eye

-> Antenna

-> Chilipod - Big claws***

-> Legs (2, 3, 4, 5)

-> Carapace - Main body and chitin abdomen covering***

Crayfish External Anatomy - Bottom View

-> Mandible - Jaws near the mouth (Side of the head)

-> Maxilliped - Behind the mandibles (3 of them)

-> Walking legs (2, 3, 4, 5)

-> Swimmerets (1, 2, 3, 4, 5) - Below the walking legs***

Subphylum Hexapoda - Insects

The most diverse, abundant, successful class of organisms

-> Gas exchange via spiracles (pores) that allow air to enter tracheae (air tubes interfacing with tissues)

-> Excretion through Malpighian tubules

-> Tympanum- hearing

Grasshopper External Anatomy

-> Antenna

-> Compound eyes

-> Simple Eyes

-> Fore and Hind Wings

-> Jumping Legs

-> Tympanum***