Across :

7. Marine plant. 8. Flat fish with a long tail like an arrow. 9. Playful and clever sea creature. 10. Some keep a pearl inside. 12. It has a broad shield, pincers and walks sideways. 13. Typical bird on the beach. 17. It has long ivory tusks, whiskers, and loves to subathe on the coast. 18. If it stings you, your skin becomes itchy and burning. 19. Its fin can be seen above the water and its teeth are feared.

Down :

1. Animal with an ink bag. 2. Hard formation in tropical seas with varied forms and colors. 3. Mollusk with eight long arms. 4. Sea bird with a large beak. 5. Small fish that carries its body vertically and has a curly tail. 6. Largest mammal on Earth. 11. Small mammal with flippers that lives in cold water. 12. Marine mollusk living in sand or mud. 14. Large crustacean with five pairs of legs and two long antenae. 15. Fish with a long body, similar to a snake. 16. Cute bird in a tuxedo.