Phylum Echinoderma

Starfish

What is the phylum Echinodermata mean

Echino= spiny & Dermea: skin

Extra: The term "Echinodermata" refers to a phylum of marine animals characterized by their spiny skin and radial symmetry. Members include starfish, sea urchins, and sea cucumbers.

Examples of animal within the phylum

Sea star/ Starfish (what we dissected)

Sea Urchin -small, globular marine creatures that look like spiky pincushions

Sea cucumber -soft, elongated, and cylindrical bodies that often resemble a cucumber, pickle, or caterpillar

Brittle star:slender, flexible arms: (like a starfish)

Sea lily- Looks like a plant colorful, feathery underwater flowers rooted to the ocean floor

Body symmetry

Radial

Cephalization

none

Germ cell layers

3 (endo, ecto, meso)

How many digestive tract openings

2 (mouth and anus)

segmentation

none

circulatory system

closed (water vascular system)

Skeletal system

Endoskeleton, water tubal skelotion

dorsal view (slides)

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Vental view (sildes)

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Vental view (sildes) pt.2

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Vental view (sildes) pt.3

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exterior/dorsal lab

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zoomed in (lab)

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vental lab

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what is the difference between doral and ventral

dorsal: top

Vental: bottom—>mouth

Detailed arms and inside lab

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middle interior (water vascular system)

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Function for the following… Madreporite plate

wart like opening to dorsal side on central disc- acts as a pressure-equalizing sieve, allowing seawater to enter the water vascular system. (locomotion, feeding and water transport)

spines

defensive armor against predators. These movable, skin-covered spines also aid in locomotion, provide structural support, and help protect delicate respiratory structures

Larson’s board- madreporite, ampulse, and tube foot (water vascular system)

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gills

skin gills, or papulae, for respiration and waste removal.

digestive glands

secreting digestive enzymes, absorbing nutrients, and storing food. They break down food, passing nutrients to the body (found in the indise of rays) 2 one each side

ray

the arms of a starfish (sea star), which typically number five, radiating from a central disc

pedicellarias

microscopic, pincer-like or forceps-like appendages on the skin used for protection, grooming, and sometimes food capture (keep surface of skin free form debris)

-both dorsal and ventral

Tube feet

-The water vascular system used primarily for locomotion, feeding, respiration, and sensory perception. These versatile tools allow sea stars, urchins, and cucumbers to crawl, climb, cling to surfaces, and manipulate prey

-Tube Feet Operation: The water flows into small sacs called ampullae connected to the tube feet.

-function like suction cup

gonads

tree-like reproductive organs located in each arm responsible for producing and releasing eggs or sperm.

radial canal

key components of a starfish's water vascular system, extending from the central ring canal along the length of each arm. They transport seawater to the tube feet through lateral canals, enabling hydraulic locomotion, feeding, and gas exchange. (vetal side)

how does water vascular system help starfish move around?

hydraulic network of canals, to power hundreds of tiny "tube feet" on their undersides. By drawing seawater in and pumping it into these tubes, the resulting water pressure forces the feet to extend, adhere to surfaces via suction, and pull the starfish forward(in the direction they want) —> shorten when relax

comes through the madreporite plate, stone canal, ring canal, readila canals, ampullle, tubes

ampullae

a hydraulic reservoir for the water vascular system. By contracting, the ampulla forces fluid into the tube foot to extend it; by relaxing, it creates suction, allowing the starfish to move, anchor, and feed.

When the ampullae contract, they push water into the tube feet, causing them to extend.

What external and internal features indicate that starfish are orginished in patterns of 5?

External:

Five Arms: Most starfish have exactly five arms radiating from a central disc.

• Oral Surface (Underside): The mouth is central, with ambulacral grooves extending down each of the five arms.

• Tube Feet: Hundreds of tube feet are arranged in rows within the five ambulacral grooves.

Internal:

• Five radial canals; five grooves

• Water Vascular System: A ring canal in the central disc connects to five radial canals, one running down each arm.

• Digestive System: The stomach often has five main pouches, and five pairs of pyloric caeca (digestive glands) extend into each arm.

• Reproductive System: Two gonads (reproductive organs) are typically found in each of the five arms.

• Nervous System: A central nerve ring connects to five radial nerves that run along each arm.

What parts of a starfish are involved in water vascular system

• Madreporite: A porous plate on the top (aboral) surface where water enters.

• Stone Canal: A tube leading from the madreporite to the central ring canal.

• Ring Canal: A central ring surrounding the mouth (esophagus) that distributes water to the arms.

• Radial Canals: Five canals running down the center of each arm.

• Lateral Canals: Small, paired canals extending from the radial canals.

• Ampullae: Bulb-like sacs at the base of each tube foot; they contract to force water into the tube feet.

• Tube Feet (Podia): External, suction-tipped tentacles that use water pressure to walk and cling.

• Polian Vesicles/Tiedemann's Bodies: Internal reservoirs and glands that help regulate water pressure and create defense cells.

(just know names)

how do starfish eat

Starfish eat by pushing their stomach out of their bodies through their mouth to digest food externally