exam 3 bio 2

Bilateria includes two main subclades:

Protostomia and Deuterostomia

Two main groups of protostomes

Lophotrochozoa (Spiralia; molluscs, annelids, flatworms, rotifers, ribbon worms, bryozoans (=ectoprocts), brachiopods)

and

Ecdysozoa (arthropods, nematodes)

What includes the majority of animal phyla and is morphologically very diverse

Lophotrochozoa

are protostomes that periodically shed their exoskeleton

Ecdysozoans

What is the clade that includes echinoderms, hemichordates (acorn worms), and chordates (our own phylum)

Deuterostomia

What are deuterostomes that have secondarily revertedto radial symmetry as adults

Echinoderms

Bilateria characteristic (Most animals belong to Bilateria)

Clade of animals with bilateral symmetry

• have a head (cephalization)

• Triploblastic: three tissue layers (Ectoderm, Endoderm, and Mesoderm)

• may or may not have a coelom (fluid-filled body cavity surrounded by mesoderm)

BILATERIA Three major clades

Lophotrochozoa - Ecdysozoa – Deuterostomia

Which clade is: animals that shed their cuticle

Ecdysozoav

Which clade is: (=Spiralia) – most with a lophophore (ring of tentacles) or trochophore (larval type)

Lophotrochozoa

Which clade is Mouth second

Deuterostomia

Lophotrochozoa and Ecdysozoa make up a clade called

Protostomia

Protostomes and deuterostomes distinguished by:

Fate of blastopore (mouth versus anus)

Fate of blastopore (mouth versus anus)

Protostomes= ? Deuterostomes: ?

Mouth and Anus

What is a lophophore?

A horseshoe-shaped ring of tentacles used for feeding

Which two phyla include some taxa with ciliated trochophore larvae?

Phylum Annelida (segmented worms) and Mollusca (mollusks)

Which two phyla are associated with a lophophore?

Phylum Ectoprocta: bryozoans and Brachiopoda: lamp shell

Flatworms (Platyhelminthes) are generally long and flat:

Acoelomates

Unlike cnidarians, flatworms lack a through-gut and instead have a:

gastrovascular cavity (digestion AND circulation)

Flatworms have organs to maintain osmotic balance called Protonephridia, which contain cells called:

Flame bulbs

Most flatworms are hermaphrodites(Many are capable of asexual reproduction), meaning they are:

Male and female

skeleton supported by hydrostatic fluid pressure

Hydrostatic skeleton

Annelids are classified as which type of worms?

COELOMATE WORMS

What divides the coelomic spaces in annelids?

septa

What is a major characteristic of an annelid's body?

made of repeating organ segments and Long & cylindrical coelomate

What does it mean that annelids have a through-gut or complete gut?

mouth to anus

Which body system is also present in annelids according to your notes?

Circulatory system

What are the lateral structures called that polychaeta annelids use for locomotion

parapodia

Polychaeta characteristic

• mostly marine, also freshwater

• have lateral parapodia for locomotion

• Many chaetae (“hairs”)

Oligochaeta characteristic

earthworms

• mostly terrestrial and freshwater

• Few chaetae

Hirudinea characteristic

leeches

• mostly freshwater

• predators and blood parasites

Importance of marine annelids

Provide food to other invertebrates and fish -70% of food in fish stomach

Modify benthic environments (Increase aerobic processes)

Provide habitat to other organisms

Bioindicator

Phylum Mollusca has 8 “classes” including:

• Polyplacophora:

• Gastropoda:

• Bivalvia:

• Cephalopoda:

Chitons - Snails, slugs - Clams, mussels, oysters, & scallops - Squid, Octopus, nautilus

toothed tongue-like organ – used for feeding (except in bivalves)

Radula

for crawling (chitons, snails) or burrowing (bivalves

Foot

space under mantle, behind visceral mass

mantle cavity

secreted by dorsal epidermis

mantle

In MOLLUSCA, where organs concentrated into

visceral mass

Ecdysozoa is a grouping of ?? phyla

8

Approximately how many known Arthropoda species exist?

More than 1 million

Approximately how many known Nematoda species exist

25,000 known, but many waiting to be discovered

Insects, spiders, crabs

Also extinct lineages; around since the Cambrian Explosion

Arthropoda

unsegmented round worms

free-living or parasitic

Nematoda

Which characteristic is shared by all taxa in Ecdysozoa?

They molt their outer covering (ecdysis).

ARTHROPODS ARE COVED BY A

JOINTED EXOSKELETON

all taxa molt their outer covering

ecdysis

Which two very diverse phyla are included in Ecdysozoa?

Arthropoda and Nematoda

 Arthropods are covered by a cuticle made of:

non-living organic layer made of Protein and Chitin that covers the epidermis

What makes the cuticle rigid and hardened in some places?

Calcium carbonate

How are arthropods similar to annelids?

Both have segmented bodies.

What are arthropod appendages adapted for?

Locomotion, sensory functions, and feeding

What does each arthropod segment have?

A pair of jointed appendages

What is the arthropod exoskeleton made of, and what is one of its functions?

Layers of protein and chitin; provides points for muscle attachment

What is the primary advantage of the arthropod exoskeleton?

 It is hard and waterproof, facilitating the invasion of land

Why do arthropods need specialized structures? And what do they book in in terrestrial taxa and aquatic taxa

For gas exchange: book lungs or trachea and Gills

Why do arthropods need to molt (ecdysis)?

to grow

What is the typical reproductive arrangement in arthropods?

Gonochoristic (separate sexes)

Which arthropod group includes extinct Paleozoic trilobites?

Trilobitimorpha

• arachnids: spiders, ticks, mites, scorpions

• horseshoe crabs

• sea spiders

Chelicerata

Which arthropod group includes centipedes and millipedes?

Myriapoda

Which group includes crustaceans

Decapods: lobsters, crabs, shrimp

Isopods: pill bugs/rollie-pollies

Copepods: tiny, planktonic

Pancrustacea

Which arthropod group includes insects?

Hexapoda

What type of immune response does the horseshoe crab rely on?

Innate immunity

Which cells are responsible for the horseshoe crab's innate immunity?

Granular amebocytes

What happens when granular amebocytes come into contact with an endotoxin?

They release a cascade of defense molecules that trigger coagulation and neutralize pathogens