Lab prac zoo 2

Phylum: Annelida

Class: Polychaeta

Family: Nereidea

Genus: Nereis

🧠 Head

• Prostomium

  • Has: eyes, antennae, palps

  • Function: sensory (light + chemicals)

• Peristomium

  • Has: tentacular cirri

  • Function: sensory + feeding coordination

🍽 Feeding

• Proboscis (pharynx)

  • Eversible, has jaws + paragnaths

  • Function: grabs prey

  • Mechanism: hydrostatic pressure (fluid pushes it out)

🪶 Body

• Segments

  • Function: repeated units → efficient movement

• Parapodia

  • Function:

    • locomotion

    • gas exchange (acts like gills)

• Chaetae (setae)

  • Function:

    • grip substrate

    • traction for crawling

❤ Circulation / nervous

• Dorsal blood vessel

  • Function:

    • circulation

    • gas exchange across thin walls

  • Note the dorsal blood vessel, and its lateral offshoots that lead to the parapodia

• Ventral nerve cord

  • Function:

    • coordination

  • If you flip the worm over so ventral is up, you may be able to see the ventral nerve cord through the body wall.

🔚 Posterior

• Pygidium

  • Has anus + cirri

  • Function:

    • waste removal

    • sensory

Prepared Slide: Parapodia

Nereis

• Notopodium + neuropodium → movement + respiration

• Cirri → sensory

• Setae → locomotion (push against substrate)

• Acicula → internal support (like a skeleton)

🔬 WHAT TO IDENTIFY

• Notopodium (dorsal lobe)

• Neuropodium (ventral lobe)

• Dorsal & ventral cirri

• Setae (chaetae)

• Acicula

Phylum: Annelida

Salmacina tribranchiata

Fragile Tubeworms

family serpulidae

they build tubes of CaCOs and never move again.

Phylum: Annelda

Family Sabellariidae - sandcastle worms (Phragmatopoma califarnica)

tubes using their tentacles to catch sand grains in the surf, then gluing them together using secreted proteins

highly regionlized, sand grain tubes, sessile worms, sedentary

1. Tentacular crown (branchiae / radioles)

• Function:

  • feeding (trap particles)

  • respiration

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2. Tube

• Serpulidae → calcium carbonate

• Sabellariidae → sand

• Function:

  • protection

---

3. Cilia on tentacles

• Function:

  • create water currents

  • move food

---

4. Operculum (if present)

• Function:

  • closes tube

---

5. Thorax vs abdomen

• Function:

  • body specialization

---

6. Uncini (tiny hooks)

• Function:

  • anchor worm in tube

Annelids 2

Prostomium

• Small, pointed

• Function: sensory (very reduced)

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Peristomium (mouth)

• Function: ingestion

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Clitellum (VERY IMPORTANT)

• Thick band (around segment ~32–37)

• Function:

  • secretes mucus during mating

  • forms cocoon for embryos

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Setae (chaetae)

• Tiny bristles

• Function:

  • traction during movement

---

Pygidium + anus

• Function: waste removal

---

Dorsal blood vessel

• Function: circulation

Order:

• Pharynx → ingestion

• Esophagus → transport

• Calciferous glands → regulate calcium / excretion

• Crop → storage

• Gizzard → grinding

• Intestine → absorption

• Typhlosole → ↑ surface area

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❤ CIRCULATORY

• Dorsal vessel → anterior flow

• Ventral vessel → posterior flow

• Aortic arches (“hearts”) → pump blood

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♻ EXCRETORY

• Nephridia

  • Function: waste removal + osmoregulation

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🧠 NERVOUS

• Brain + ventral nerve cord

• Function: coordination

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🧬 REPRODUCTIVE (HIGH YIELD)

• Seminal vesicles → make sperm

• Spermathecae → store sperm

• Ovaries / oviducts → eggs

🔬 IDENTIFY + FUNCTION

• Circular muscle

  • elongates body

• Longitudinal muscle

  • shortens body

• Coelom

  • fluid-filled → hydrostatic skeleton

• Dorsal vessel / ventral vessel

  • circulation

• Ventral nerve cord

  • coordination

• Typhlosole

  • increases absorption

Cross section of earthworm

1. 🟣 INTESTINE (CENTER — BIGGEST STRUCTURE)

• Looks like: large circular/oval structure in middle

• Often has a fold inside

👉 Function:

• digestion + absorption

2. ⭐ TYPHLOSOLE (VERY IMPORTANT)

• Looks like: fold projecting into intestine (like a flap or ridge)

👉 Function:

• increases surface area for absorption

3. 💧 COELOM (EMPTY SPACE AROUND ORGANS)

• Looks like: clear/white space surrounding intestine

👉 Function:

• hydrostatic skeleton (helps movement)

4. 💪 MUSCLE LAYERS (AROUND OUTER EDGE)Circular muscle

• Thin layer closer to outside

Longitudinal muscle

• Thicker layer just inside circular

👉 In your images:

• Outer pink ring = body wall muscles

👉 Function:

• movement (elongation + shortening)

5. 🧠 VENTRAL NERVE CORD

• Location: bottom (ventral side)

• Looks like: small oval/round structure

👉 In your pics:

• Look at lower part of the circle

• Small dense structure near bottom

👉 Function:

• coordination

6. ❤ BLOOD VESSELSDorsal blood vessel

• Top side (above intestine)

• Small circular structure

Ventral blood vessel

• Bottom side (below intestine)

👉 Function:

• circulation

7. ♻ NEPHRIDIA (if visible)

• Tubular structures off to sides

• Not always clear

👉 Function:

• excretion

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8. 🪶 CHLORAGOGEN TISSUE

• Looks like: fuzzy layer around intestine

👉 Function:

• metabolism + storage (liver-like)

Cross-section of a glossiphonid (snail-eating) leech

• Reduced coelom

  • replaced by sinuses

• Botryoidal tissue

  • involved in storage/excretion

• Gut with caeca

  • storage of blood

• Muscle layers

  • strong → movement

• No true circulatory system

  • fluid channels instead

Whole-mount of a glossiphonid leech

• Anterior sucker

  • feeding + attachment

• Posterior sucker

  • anchoring

• Proboscis

  • feeding

• Crop

  • stores blood

• Intestine

  • digestion

• Rectum

  • waste

• Testes / ovaries

  • reproduction

Preserved urechis

🔬 IDENTIFY + FUNCTION

• Anterior sucker (ventral)

• Posterior sucker

• Clitellum

• Annuli (many rings per segment)

• Eyes (dorsal)

• Mouth + anus

Preserved leech