Phylum Platyhelminthes (Flatworms) Acoelomates Phylum Nemertina (Ribbon Worms)

Phylum Platyhelminthes Phylum Nemertina FIGURES TO KNOW: (FLATworms) (ribbon worms) 3 CLASSES Phylum Platyhelminthes: Class Trematoda Fig. 3.1 - Know that A represents three body layers (not 2 as in Cnidaria) (flukes) Class Cestoda Proboscis in rhynchocoel (tapeworms) Fig. 3.2 - 1, 2 (also GVC), 3, 4, 5 (under the pharynx), 6, 7 Closed Circulatory System 2 Suckers Fig. 3.3 - Realize that Turbellarians are monoecious (=hermaphroditic) (1 for attachment) Proglottids Fig. 3.4 - All; change proboscis to pharynx, strike pharyngeal cavity, change ‘mouth’ to ‘pharyngeal Class Turbellaria Scolex (free livin’ planarians) opening’, ‘intestinal branch’ = ‘intestinal caecum/caeca’ Tri-lobed gut Fig. 3.5 - Know oral sucker, pharynx, caeca, ventral sucker, uterus, yolk gland, eggs, ovary, seminal receptacle, testes Fig. 3.6 - Know general life cycle of tapeworms (2 hosts) Dorsoventrally Flattened Fig. 3.7 - A, D, E, & 1, 2, 6, 8, 10, 11, 17, 18 COMPLETE DIGESTIVE SYSTEM Protonephridia (mouth->gut->anus) (flame cells) Allows for compartmentalization of digestive Phylum Nemertina: tract into areas for ingestion, storage, digestion and egestion. These can be simultaneous! Fig. 4.1 - A-D, note location of proboscis/rhynchocoel in relation to digestive tract.

Phylum Cnidaria Fig. 4.2 - All of A; all of B, except epidermal glands & connective tissue/muscle layer. 3 CLASSES Acoelomates Fig. 4.3 - Fill in labels & know all

Phylum Porifera Bilateral Symmetry (sponges) 3 TYPES At least 3 tissue layers (TRIPLOblastic endo-, meso-, ectoderm) At least ORGAN Level of Organization At least 2 tissue layers (diploblastic) At least Tissue Level of Organization At Least Cellular Level of Organization

Kingdom Animalia Hypothetical common ancestor ACOELOMATES

PHYLUM PLATYHELMINTHES & PHYLUM NEMERTINA The ACOELOMATE Condition

Ectoderm

Mesoderm

Endoderm

Lumen of gut

Any triploblastic organism which lacks a body cavity is said to be an acoelomate... PLATYHELMINTHES ‘Flatworms’ • ORGAN grade of body organization

• TRIPLOBLASTIC

• MESENCHYME = Middle layer derived from mesoderm germ layer = space-filling packing tissue

• ACOELOMATE - Mesoderm obliterates the blastocoel in the embryo PLATYHELMINTHES 3 main classes

•CLASSTurbellaria - Free-living flatworms

•CLASSTrematoda - Endoparasitic Flukes

•CLASSCestoda - Endoparasitic Tapeworms Marine flatworms…

But what we saw in lab was a freshwater flatworm. It was brown and looked as if it were boss-eyed.

PHYLUM Platyhelminthes CLASS Turbellaria M

PO P

PO P M

I

Note extensible pharynx (P), pharyngeal opening (PO), mouth (M) & intestine (I) [fig 3.2-A] PHYLUM Platyhelminthes CLASS Turbellaria

Anterior Pharyngeal region Posterior

cs through anterior of organism [fig 3.4] aka Batman’s plane. Note No pharynx, only caeca PHYLUM Platyhelminthes CLASS Turbellaria

c.s. through pharyngeal region [fig 3.4] Note Pharynx, gastric caeca & Mesenchyme (Cilia!?) Fist of 2 Acoelomate c.s PHYLUM Platyhelminthes CLASS Trematoda

V

A

View of whole fluke organism. Note the two suckers. Anterior (A) one is for feeding, the ventral (V) one is for attachment OS

P

C

C

PHYLUM Platyhelminthes VS CLASS Trematoda

Anterior end of fluke. Note oral sucker (OS), pharynx (P), caeca (C) & ventral sucker (VS) (for attachment) [fig 3.5] U

C E O

O

PHYLUM T Platyhelminthes C CLASS Trematoda

Note eggs E, ovaries O, shell gland, caeca C, uterus U and testes T [fig 3.5] PHYLUM Platyhelminthes CLASS Cestoda

Scolex (I) and maturing proglottids.

The most reproductively mature sections are at the posterior end of the tapeworm.

What are these sections called? R

S

S

PHYLUM Platyhelminthes CLASS Cestoda

Scolex region. Note rostellum (R) (rings of hooks) & suckers (S) for attachment [fig 3.7-A] Sperm in from partner Sperm exit here to enter another partner’s proglottid

Speckled background = Uterus Testes & Shell Gland

Ovary Uterus will swell with many out- PHYLUM pockets as the Platyhelminthes eggs develop CLASS Cestoda

Mature proglottid w/ reproductive structures [fig 3.7-D] Uterus has swollen with eggs - fertilized with a partner tapeworm’s sperm

PHYLUM Platyhelminthes CLASS Cestoda

Gravid proglottid chock full o’ eggs [close-up of fig 3.7-E]