chaeognaths, echinoderms, and hemichordates

The blastopore becomes the anus

deuterostome

becomes the mouth

protostomes

Arrow worms

phylum chaetognatha

Evolutionary position is still debated

phylum chaetognatha

Pelagic marine predators

phylum chaetognatha

Highly specialized for their planktonic existence

phylum chaetognatha

Horizontal fins bordering the trunk are used inflation rather than inactive swimming

phylum chaetognatha

Has a unique water vascular system

Phylum echinodermata

Has a pentardial

Phylum echinodermata

Has exoskeleton with spines

Phylum echinodermata

digestive system is complete

Phylum echinodermata

Are free swimming bilateral larvae

Phylum echinodermata

Excretory organs absent

Phylum echinodermata

No other group has such complex organ system and have radial symmetry

Phylum echinodermata

found from marine intertidal to abyssal regions

Phylum echinodermata

perphaps evolved radially as an adaptation to sessile existence

Phylum echinodermata

due to _______ ___________ are not often preyed on

spiny structures

A few fish and sea otters are adapted to feed on ______ ______

sea urchins

___ ___ feed on molluscs, crustaceans, and other invertebrates

sea stars

Seastars are a _______ ______ because it help maintain species diversity

keystone predator

sea stars commonly called starfishes

class asteroida

can regenerate lost parts by casting off injured arms and regenerate new ones

sea stars

About 1,500 living species that range from 1cm to more than 1m across with variable colors and structural features

class asteroida

common on the east coast of the u.s and often used in school laboratories

asterias sp.

is common on the west coast(keystone predator)

pisaster sp.

In echinoderms have a greatly diversified within the habitat and range from creeping form with _______ ______, Scavenging, Herbivorous, _____ predatory forms, and predaceous _______ ______

filter feeding; pelagic; inter tidal zone

was formerly considered a subphylum of chordates based on presence of gill slits and a rudimentary notochord

Phylum Hemichordata

The _________ is really a buccal diverticulum called stomochord in the Phylum Hemichordata

notochord

Not homologous to chordate notochord

Phylum Hemichordata

generally bottom dwellers, living in shallow waters with cosmopolitan distribution but are fragile and secretive

Phylum Hemichordata

most are sedentary or sessile while some are colonial, living in tubes

Phylum Hemichordata

are acronworms

phylum enteropneusta

are sluggish, wormlike creatures that live in burrows in the mud and sand

acronworms

the products is the active part of the animal

phylum enteropneusta(acronworms)

it probes its surrounding and collects food in mucous strands

phylum enteropneusta(acronworms)

is similar to that of Enteropneusta with modifications due to sedentary lifestyle

class pterobranchia

small animals usually 1 to 7mm in length

class pterobranchia

many individuals may live together in collagenous tubes

class pterobranchia

in class pterobranchia, _____ are not connected but live independently in the tubes and extend their crown of tentacles out through openings

zooids

Pharyngeal and slits shares similar characteristics

echinoderms and chordates

Diffuse epidermal nervous system but dorsal nerve cord in collar region hemichordates is not similar to dorsal nerve cord of chordates shares similar characteristics

echinoderm and chordates

________ is now placed as a sister taxon to the combined group of echinoderm and hemichordates

chordata